COPYRIGHT,  1916, 

BY 

JOHN  WILEY  &  SONS,  INC. 


Stanbopc  flbreas 

F.    H.  GILSON   COMPANY 
BOSTON,  U.S.A. 


PREFACE 


ANALYSIS,  that  valuable  tool  of  Science,  can  obviously  be  used 
only  when  the  basal  elements  or  units  are  recognized  and  under- 
stood. In  geologic  science  it  was  early  realized  that  a  far 
greater  insight  into  the  character  and  significance  of  rocks  than 
that  afforded  by  their  bulk  composition  is  gained  by  knowledge 
of  the  kinds  and  proportions  of  their  constituent  minerals,  which 
stand  in  relation  to  geology  much  as  do  the  elements  to  chemistry. 
In  consequence,  mineralogy  changed  from  an  engaging  phase 
of  the  collecting  mania  to  a  fundamental  requisite  in  our  study  of 
the  rocks,  and  microscopic  petrography  evolved  as  its  specialized 
application  to  these  natural  associations  of  the  minerals,  whereby 
understanding  of  the  nature  and  origin  of  materials  forming  our 
planet  has  been  greatly  extended. 

One  class  of  geologic  bodies,  the  ores,  relatively  neglected  in 
earlier  stages  of  geologic  advance,  have  of  late  years  received  in- 
creasing attention,  partly  because  of  their  inherent  interest, 
partly  because  they  so  sensitively  record  as  to  illuminate  many 
complex  geologic  processes,  but  above  all  because  of  their  enor- 
mous economic  importance.  Microscopic  study  of  ores,  however, 
was  on  a  basis  now  known  to  be  one-sided  and  inadequate,  until 
application  of  the  reflecting  microscope,  virtually  beginning  with 
Campbell's  paper  in  1906,  permitted  as  minute  and  satisfactory 
observation  of  the  opaque,  metalliferous  minerals,  as  had  long  been 
possible  for  the  transparent  varieties.  This  new  method,  quickly 
adopted  by  numerous  American  investigators,  has  already  demon- 
strated its  immeasurable  value  and  is  rapidly  disclosing  new 
and  unsuspected  truths  regarding  the  opaque  minerals.  Indeed, 
it  opens  an  entire  new  field  of  geologic  science  that  promises  to 
do  for  the  ores  what  petrography  has  done  for  the  rocks;  for 
this  the  name  "  Mineralography  "  is  herein  proposed. 

One  serious  handicap,  lack  of  adequate  means  for  identifying 
the  mineral  varieties,  has  hindered  the  fullest  development  and 
delayed  wider  adoption  of  this  new  method.  Several  lists  of 

iii 

340247 


iv  PREFACE 

properties  of  certain  minerals  and  one  or  two  essays  at  more 
systematic  identification  have  appeared.  However,  the  necessity 
for  completeness,  emphasized  by  Dana,  for  mineral  determina- 
tion in  general,  is  even  greater  for  the  opaque  varieties,  owing 
to  the  closely  similar  properties  of  many.  In  other  words,  no 
determinative  scheme  for  the  opaque  minerals  can  be  satisfactory 
or  reliable  unless  it  includes  them  all.  It  cannot  be  concluded, 
for  example,  that  a  given  mineral  grain  is  tetrahedrite,  because 
in  certain  tests  it  behaves  like  that  species  —  it  is  necessary  to 
prove  that  the  grain  in  question  actually  ia  tetrahedrite  and  not 
something  else,  such  as  bournonite  or  polybasite,  which  closely 
resemble  it  in  many  ways;  even  the  probabilities  of  the  case 
cannot  be  relied  upon,  for  it  is  now  evident  that  many  supposedly 
rare  minerals  are  actually  rather  common  in  sulphide  ores,  are 
often  of  important  geologic  significance,  and  can  in  no  case  be 
safely  ignored. 

The  scheme  of  determination  of  opaque  minerals  here  presented 
embraces  nearly  every  species  of  recognized  identity  that  could  be 
secured  from  the  principal  mineral  collections  of  the  United  States, 
and  thus  includes  many  names  probably  familiar  only  to  the  pro- 
fessional mineralogist.  One,  who,  like  the  geologist  of  a  mine, 
may  wish  simply  to  examine  the  intimate  relations  of  the  minerals 
in  a  familiar  ore,  might  therefore  conclude  that  this  treatise  is 
too  purely  scientific  and  detailed  for  the  needs  of  a  busy,  prac- 
tical man.  But  he  may  be  assured  that  even  the  simplest  sulphide 
ore  is  more  than  likely  to  hold  unsuspected  constituents  whose 
identity  and  significance,  when  determined,  may  prove  of  direct 
value. 

Nor  is  specialized  training  or  technique  a  pre-requisite  to  intelli- 
gent use  of  this  plan  of  identification.  Intricacies  of  crystallog- 
raphy and  optics,  essential  to  thin-section  petrography,  and 
generally  mastered  only  under  expert  instruction,  are  not  here 
involved;  absence  of  the  diagnostic  optical  properties  of  trans- 
parent minerals  is  balanced  by  ease  of  applying  physical  and 
chemical  tests  to  the  polished  surface;  even  the  microchemical 
reactions  need  not  be  understood  to  be  used  correctly.  Prac- 
tically the  only  requirement  is  to  follow  the  simple  directions 
indicated  and  the  plan  of  indexing  employed  will  lead  almost 
automatically  to  the  proper  result.  The  entire  scheme  may  be 
mastered  by  any  one  possessing  common  sense  and  a  good  eye. 


PREFACE  V 

In  the  matter  of  equipment,  likewise,  the  demands  are  modest. 
Though  elaborate  instruments  are  advisable  under  certain  cir- 
cumstances, satisfactory  results  may  be  secured  with  the  simplest 
outfit.  Almost  any  microscope,  for  whatever  purpose  designed, 
may  be  adapted  for  this  study  at  slight  expense  by  attaching  a 
prism  reflector  that  permits  Daylight  illumination.  Or  a  satis- 
factory microscope  may  be  had  complete  for  less  than  $30.00. 
Mounting  clay,  glass  tubing,  and  a  few  reagents  complete  the 
necessary  equipment  for  examination,  while  the  specimens  may 
be  prepared  without  delay  by  means  of  a  file,  emery  cloth,  chamois 
skin  and  rouge,  if  better  means  are  not  at  hand.  For  the  opaque 
minerals  this  determinative  method  should  in  time  largely  sup- 
plant blowpipe  analysis,  since  it  can  in  most  cases  yield  better 
and  quicker  results  with  equal  or  greater  simplicity,  and  perhaps 
as  cheaply,  if  widely  adopted. 

Notwithstanding  its  fitness  for  elementary  and  for  practical 
determinative  uses,  this  text  is  intended  equally  for  serious  re- 
search. Mineralographic  methods  show  that  to  a  far  greater 
degree  than  is  true  of  the  transparent  species,  the  sulphide  min- 
erals tend  to  be  microscopically  mingled  and  intergrown  in  most 
intimate  fashion,  also  that  they  may  undergo  serious  alteration 
of  which  no  outward  sign  may  exist.  In  consequence,  the  compo- 
sition ascribed  to  many  species  is  discredited,  the  right  to  stand 
as  independent  species  is  disproved  for  others,  and  new  species 
as  yet  unnamed  have  appeared,  —  even  in  specimens  from  the 
best-known  collections  of  the  country  identified  unquestionably 
with  the  greatest  accuracy  possible  hitherto.  In  short,  the  min- 
eralogy of  the  sulphides  needs  complete  revision.  Henceforth, 
he  who  describes  or  analyzes  an  opaque  mineral,  without  first 
establishing  its  purity  by  closest  mineralographic  scrutiny,  dis- 
counts his  own  reliability  and  that  of  his  results. 

In  more  practical  directions,  the  wide  applicability  of  this  method 
of  mineral  investigation  may  be  indicated  by  a  list  of  typical  problems 
it  has  solved  in  materials  submitted  to  the  Harvard  laboratories: 

(a)  Method  of  occurrence  and  state  of  combination  of  gold, 
silver  and  other  metals  in  ores  as  affecting  choice  of  treatment 
to  be  adopted. 

(6)  Condition  of  metals  lost  in  mill  tailings  (up  to  100-mesh 
powders)  and  in  slags,  that  suitable  improvements  in  recovery  may 
be  applied. 


Vi  PREFACE 

(c)  Extent  and  effect  of  roasting  and  of  subsequent  leaching 
of  sulphide-bearing  tailings  from  concentration. 

(d)  Character   of    furnace   mattes,    whether   homogeneous   or 
complex. 

(e)  Various  practical  geological  problems  difficult  or  impossible 
of  solution  otherwise,  such  as  determining  whether  metal  values 
in  churn-drill  pulps  are  primary  or  are  due  wholly  or  in  part  to 
secondary   enrichment;     also    distinction   between   primary   and 
secondary  chalcocite. 

The  investigation  embodied  in  this  book  originated  as  one  of 
the  essential  preliminaries  to  a  study  of  mineral  occurrence  and 
alteration  being  carried  on  by  the  Secondary  Enrichment  Inves- 
tigation. It  has  been  steadily  pursued  by  Dr.  Murdoch  since 
1911  and  has  had  the  benefit  of  trial  in  actual  practice  by  members 
of  the  Secondary  Enrichment  staff  and  in  the  Harvard  labora- 
tories during  the  last  two  years,  also  in  the  Geological  Depart- 
ment of  the  Massachusetts  Institute  of  Technology  during  the 
past  year. 

L.  C.  GRATON. 

CAMBRIDGE,  MASS. 
August,  1915. 


CONTENTS 


PAGE 


FRONTISPIECE „ '.£ 

PREFACE iii-vi 

INTRODUCTION 1 

HISTORY 1 

IMPORTANCE  OF  THE  SUBJECT 3 

PREVIOUS  WORK 4 

SCOPE  OF  PRESENT  WORK 14 

BIBLIOGRAPHY 16 

TECHNIQUE  OF  MINERALOGRAPHY 19 

POLISHING 19 

MOUNTING 23 

EXAMINATION 24 

MAGNIFICATION 25 

PHOTOGRAPHING 25 

COLOR  COMPARISON 26 

HARDNESS  DETERMINATION 29 

MlCROCHEMICAL  TESTS 30 

METHOD  OF  APPLICATION 30 

REACTIONS 31 

REAGENTS 32 

MINERAL  COMPOSITION  AND  IDENTITY 33 

OBSERVED  MIXTURES 36 

PROBABLE  MIXTURES  AND  DOUBTFUL  MINERALS 38 

PLAN  OF  CLASSIFICATION 40 

COLOR 40 

COLORED 40 

WHITE 40 

GRAY 41 

TRANSPARENT  AND  GANGUE  MINERALS 41 

EFFECT  OF  SURFACE  ON  COLOR 42 

HARDNESS 42 

MlCROCHEMICAL  TESTS 42 

EXPLANATION  OF  TABLES 42 

DIRECTIONS  FOR  USE 42 

EXAMPLES 43 

'  CROSS-REFERENCES 44 

ABBREVIATIONS 45 

OUTLINE  OF  THE  CLASSIFICATION 47 

TABLES  FOR  MINERAL  IDENTIFICATION 57-152 

MISCELLANEOUS  TABLES 153 

CONDENSED  DETERMINATIVE  TABLE 154 

ODOR  AND  STREAK  OF  MINERALS 156 

MINERALS  TABULATED  BY  ELEMENTS 157 

INDEX  OF  MINERALS 163 

vii 


MICROSCOPICAL  DETERMINATION   OF 
THE   OPAQUE   MINERALS 


*  INTRODUCTION 

HISTORY 

THE  microscope  was  first  applied  to  the  study  of  thin  sections 
of  transparent  minerals  in  1828  by  Nicol,41  but  the  first  prac- 
tical use  of  it  in  studying  thin  sections  was  made  in  1851  by 
Sorby.40  This  method  of  investigation  has  now  been  brought 
to  a  high  point  of  efficiency  and  perfection.  By  means  of  the 
petrographic  microscope,  transparent  minerals  can  be  identified, 
and  their  most  minute  relationships  observed,  so  that  this  instru- 
ment has  gone  far  towards  solving  many  of  the  important  prob- 
lems connected  with  ore  and  rock  genesis,  mineral  constitution 
and  alteration.  The  ordinary  petrographic  microscope  is  thus 
entirely  satisfactory  for  the  study  of  minerals  which  appear 
transparent  in  thin  section,  but,  for  the  following  reasons,  loses 
much  of  its  value  when  applied  without  modification  to  the  study 
of  ores,  in  which  most  of  the  important  minerals  are  opaque. 

In  grinding  a  thin  section,  one  of  the  fundamental  requisites  is 
to  secure  a  plate  of  uniform  thickness,  as  nearly  plane  as  possible 
on  both  sides,  with  no  difference  in  relief  developed  between 
hard  and  soft  minerals.  In  this  way  comparison,  which  would 
not  be  possible  otherwise,  may  be  made  of  the  different  optical 
properties  of  minerals.  But  even  with  modern  methods  of  prep- 
aration, if  the  surface  is  ground  so  that  the  harder  minerals  are 
perfectly  smooth  and  shiny,  the  softer  ones  will  be  polished  out, 
and  the  section  will  go  to  pieces;  consequently  the  best  that 
can  be  done  in  producing  the  plate  of  uniform  thickness  is  to  leave 
its  surface  microscopically  rough.  When  observed  by  means  of 
reflected  light,  the  opaque  minerals  in  such  a  section  appear  so 
rough  that  only  the  larger  relations  are  usually  apparent  and  they 
reflect  in  the  desired  direction  so  little  light,  that  it  is  frequently 

Note.  —  The  determinative  tables  of  this  book,  in  practically  their  present  form,  con- 
stitute the  principal  portion  of  a  thesis  presented  as  part  of  the  requirement  for  the 
degree  of  Doctor  of  Philosophy  at  Harvard  University. 


2  MICROSCOPICAL  DETERMINATION 

difficult  or  impossible  to  differentiate  between  closely  similar 
minerals,  without  some  further  means  of  testing.  Moreover, 
with  vertical  illumination,  the  coverglass  on  a  thin  section  reflects 
much  of  the  light  before  it  reaches  the  section,  so  a  dim  image  is 
produced,  and  the  difficulty  of  accurate  observation  is  increased. 
Until  recently,  however,  most  microscopic  investigation  of  the 
sulphide  minerals  has  been  accomplished  in  this  way. 

In  1814,  Berzelius6  polished  a  section  of  pyrrhotite,  in  the  hope 
of  ascertaining  why  the  composition  was  variable,  and  found 
another  sulphide  intergrown  with  it,  showing  a  different  color. 
He  does  not  mention  using  a  microscope  in  this  examination.  In 
1863,  Sorby40  published  an  account  of  the  microscopic  examination 
of  polished  surfaces  of  iron.  His  methods  of  examination  were 
practically  those  use.d  today  by  metallographers,  though  of  course 
the  apparatus  and  methods  of  polishing  have  since  been  improved. 
This  marked  the  beginning  of  the  science  of  metallography,  but 
the  method  was  not  applied  to  the  examination  of  opaque  minerals 
until  1885,  when  Baumhauer4  polished  some  bornite  and  noted 
microscopically  admixed  chalcocite,  chalcopyrite  and  galena,  and 
gave  some  micro-drawings  of  the  sections.  Then,  in  1887,  A.  A. 
Julien,21  in  studying  pyrite,  examined  the  smooth  and  etched 
natural  surfaces  of  crystals  with  the  Sorby  reflecting  microscope. 
He  did  not  artificially  polish  any  of  his  specimens.  In  1904,  E. 
Hussak19  studied  microscopically  some  polished  surfaces  of  titanif- 
erous  magnetite  from  Brazil,  and  also  etched  and  photographed 
them. 

About  1900,  William  Campbell,  a  metallurgist,  polished  and 
examined  under  the  metallographic  microscope,  some  specimens 
of  natural  pyrrhotite  in  order  to  ascertain,  if  possible,  the  cause 
of  their  magnetic  quality;  he  was  at  once  so  much  impressed 
with  the  possibilities  of  this  method  for  the  study  of  opaque 
ores,  that  he  determined  to  pursue  the  subject  further.  In  1906 
he  published  a  paper12  describing  rather  fully  the  application 
of  metallographic  methods  to  opaque  minerals,  giving  details 
of  manipulation  and  examination  of  specimens.  This  paper, 
in  which  for  the  first  time  was  emphasized  the  extreme  value 
to  the  geologist  and  mineralogist  of  the  method  so  successfully 
employed  for  metals  and  alloys,  may  be  said  to  mark  the  be- 
ginning of  the  serious  application  of  the  reflecting  microscope  to 
opaque  ores.  Though  Campbell's  paper  attracted  a  considerable 

t<  ,     , 


OF  THE  OPAQUE  MINERALS  3 

amount  of  attention  at  the  time  of  its  publication,  for  several 
years  following  little  was  published  involving  the  use  of  this 
method.  More  recently  there  has  been  rapidly  increasing  evi- 
dence of  the  use  of  this  means  of  examination  by  students  of 
mining  geology,  though  its  practice  is  still  mainly  confined  to 
this  country. 

IMPORTANCE  OF  THE  SUBJECT 

The  examination  of  opaque  minerals  and  ores  by  the  reflecting 
microscope  is  now  established  as  a  definite  branch  of  geologic 
investigation,  and  merits  a  designation  of  its  own.  For  this,  the 
term  "  mineralography  "  is  suggested;  it  is  analogous  to  "  pe- 
trography," which  now  commonly  implies  the  microscopic  study 
of  rocks,  and  to  "  metallography,"  the  microscopic  study  of 
metals  and  alloys,  while  its  etymology  signifies  its  relation  to 
the  broad  science,  mineralogy,  as  petrography  is  related  to  the 
more  inclusive  subject,  petrology.  The  possible  objection  that 
the  subject  is  really  narrower  than  its  name  implies,  since  it  deals 
with  only  one  division  of  minerals,  is  also  applicable  to  crystal- 
lography, which  does  not  claim  to  usurp  the  entire  field  of  crystal 
study,  and  to  metallography,  which  deals  only  with  certain 
features  of  metals;  and  indeed,  it  is  because  petrography  has  in 
practice  been  limited  to  less  than  its  name  implies,  that  there  is 
room  and  need  for  this  new  subject,  mineralography.  Petrog- 
raphy and  mineralography  are  complementary,  and  together 
will  cover  both  the  rocks  and  the  ores. 

By  the  methods  of  mineralography  the  appearance  and  struc- 
tures of  opaque  minerals  can  be  observed  as  accurately  and  easily 
as  those  of  transparent  species  in  the  ordinary  thin  section. 
Mining  geologists  are  beginning  to  realize  that  the  careful  micro- 
scopic study  they  have  been  giving  to  the  transparent  gangue 
minerals  in  ores  yields  only  a  part  of  the  information  required, 
and  that  it  is  necessary  to  gain  equally  detailed  and  accurate 
knowledge  concerning  the  microscopic  relations  of  the  opaque 
minerals,  which  are,  in  fact,  the  most  important  constituents  of 
most  ores.  It  is  in  this  direction  that  the  subject  will  find  its 
widest  economic  application. 

Mineralography  should  also  be  of  the  greatest  assistance  to 
the  mineralogist,  in  determining  the  purity  of  opaque  minerals. 
Examination  of  several  thousand  ore  and  mineral  specimens  shows 


4  MICROSCOPICAL   DETERMINATION 

that  even  well-crystallized  material  is  commonly  very  impure 
and  quite  unsuited  for  accurate  determination  of  mineral  compo- 
sition. To  secure  a  few  grams  of  even  the  common  sulphide 
minerals  unmixed  with  other  species  usually  requires  long  search; 
rarely  does  a  polished  surface  a  centimeter  square  show  the 
presence  of  only  one  constituent.  It  also  has  been  shown  that  the 
variable  composition  or  doubtful  character  of  a  number  of  minerals 
is  due  to  mechanical  mixture  of  two  or  more  constituents,  and 
undoubtedly  others  will  be  similarly  explained.  Accordingly, 
there  is  imperative  need  for  mineralographic  examination  to 
accompany  chemical  investigation  of  the  opaque  minerals,  because 
without  it,  the  significance  of  the  analysis  must  be  in  doubt. 
Besides,  it  will  save  the  time  and  expense  of  analysis  of  material 
that  is  in  reality  impure. 

This  branch  of  geologic  science  is  undoubtedly  one  of  great 
promise,  capable  and  worthy  of  development  to  a  high  point  of 
efficiency,  and  comparable  in  value  to  the  study  of  transparent 
minerals  by  the  petrographic  microscope. 

Before  any  conclusions  can  be  drawn  from  the  study  of  a  pol- 
ished section  it  is  absolutely  essential  to  be  able  to  identify  the 
minerals  it  contains.  As  yet,  however,  no  comprehensive  sys- 
tematic scheme  of  opaque  mineral  identification  has  been  published, 
and  accordingly  each  investigator  has  had  to  work  out  his  own 
problems  in  identification,  with  little  help  from  others.  It  is 
clear  from  the  fact  that  various  minerals  are  mentioned  in  papers 
dealing  with  mineralographic  descriptions,  that  the  writers  have 
devised  some  means  of  identification,  but  in  most  cases  these  are 
not  given,  and  undoubtedly  some  determinations  have  been 
erroneous. 

PREVIOUS  WORK 

The  following  paragraphs  briefly  summarize  all  the  published 
data  on  opaque  mineral  identification  found  in  careful  search 
through  the  literature. 

1814.  —  Berzelius6  sliced  and  polished  pyrrhotite,  and  observed 
that  it  was  veined  through  by  a  different  colored  mineral,  so  that 
he  could  distinguish  the  two  by  their  colors.  He  did  not  use  a 
microscope. 

1885.  —  Baumhauer4  noted  the  importance  and  desirability  of 
microscopic  examination  of  polished  surfaces  of  opaque  minerals 
in  reflected  light,  since  meteorites  had  been  successfully  studied 


OF  THE  OPAQUE   MINERALS  5 

in  that  way.  He  examined  polished  sections  of  massive  bornite 
from  Chloride,  N.  M.,  and  saw  many  included  areas  of  bluish 
gray  chalcocite.  He  developed  different  crystal  grains  in  the 
bornite  by  etching  a  short  time  with  HNOa,  and  also  observed 
that  the  chalcocite,  etched  a  short  time  with  concentrated  HN03, 
developed  "  a  kind  of  striation"  having  different  directions  in 
different  grains.  Some  areas  etched  more  deeply  than  others. 
He  noted  that  chalcocite  was  as  hard  as  bornite,  and  showed 
no  cleavage.  He  also  noted  a  little  chalcopyrite,  but  did  not 
describe  its  characteristics,  and  certain  areas  of  a  mineral  whiter 
than  chalcocite,  full  of  triangular  pits,  which  he  suggested  might 
be  galena,  but  about  which  he  would  not  commit  himself.  It  is 
clear  from  his  description  and  drawing  that  it  was  really  galena, 
as  the  characteristics  he  describes  are  conclusive  and  his  drawing 
confirms  these. 

1887. l —  Julien21  described  the  appearance  of  crystal  faces  of 
pyrite. 

1897-8.  —  Beijerinck5  wrote  a  very  important  paper  on  the 
electric  conductivity  of  minerals,  especially  the  opaque  varieties. 
He  sometimes  used  polished  surfaces  to  give  the  "  pattern  "  of 
impurities  on  a  gelatine  plate,  formed  by  local  electric  currents 
set  up  by  the  differences  of  potential  of  the  different  minerals. 
He  said  that  he  discovered  impurities  in  his  material  this  way. 
He  did  not,  however,  study  these  polished  sections  with  the 
microscope. 

1904.  —  Hussak19  polished  titaniferous  magnetite,  etched  it  with 
strong  HC1,  and  thereby  developed  a  distinction  between  ilmenite, 
which  did  not  blacken,  and  magnetite,  which  did. 

1906.  —  Campbell12  suggested  the  possibilities  of  identification 
by  different  reagents,  and  by  different  colors  and  appearances  of 
minerals. 

-  Campbell  and  Knight13  described  the  appearance  of  niccolite, 
smaltite,  argentite,  silver,  and  two  unknown  minerals,  from  Cobalt, 
Ontario,  but  gave  no  record  of  tests. 

1907.  —  Campbell  and  Knight14  summarized  briefly  a  few -char- 
acteristics of  the  Sudbury  ore  minerals  as  follows: 

Chalcopyrite.  —  Clear  yellow  color.     Takes  a  good  polish. 
H.  -  4. 

Its  color  is  its  chief  distinguishing  characteristic. 


6  MICROSCOPICAL  DETERMINATION 

Magnetite.  —  Steel  gray  color.  Polishes  very  well*  but 
more  slowly  than  chalcopyrite.  H.  =  5.5  —  6.5.  It  etches 
differentially  along  cleavage  planes,  often  yielding  a  "  grid- 
iron "  structure. 

Pentlandite.  —  Light  bronze  color.  Polishes  better  than 
pyrrhotite;  is  not  so  brittle.  H.  =  4.  Sometimes  shows  a 
distinct  cleavage.  Easily  distinguished  from  pyrrhotite  by 
etching. 

Pyrite.  —  Pale    brass    color.      Polishes    with    difficulty. 
Retains  scratches  long  after  other  constituents.     H.  =  6  - 
6.5;   therefore  it  polishes  in  relief. 

Pyrrhotite.  —  Light  bronze  color,  similar  to  pentlandite. 
More  brittle  than  pentlandite  and  shows  a  more  pitted 
surface.  H.  =  4.  By  immersing  in  hot  HC1  (1  acid  to  1 
water)  pyrrhotite  is  attacked,  pentlandite  is  not. 

1908  —  Simpson37  summarized  the  characters  of  a  few  minerals 
as  follows: 

Bornite.  —  Copper  red  to  pinchbeck  brown  in  color. 
H.  =  3.  Easily  attacked  by  nitric  acid.  This  acid  gives 
the  bornite  a  tarnished  appearance.  When  with  pyrite,  an 
extremely  smooth  surface  of  this  mineral  is  difficult  to 
obtain,  on  account  of  the  great  difference  in  hardness  be- 
tween the  two.- 

Chalcocite.  —  Blackish  lead  gray  in  color.  H.  =  2. 
When  etched  with  nitric  acid,  a  distinct  blue  color  is  ob- 
tained. This  is  the  best  means  of  identification. 

Chalcopyrite.  —  Color,  brass  yellow.  H.  =  3.5  —  4.  The 
color  is  the  best  characteristic.  Soluble  in  nitric  acid. 

Enargite.  —  Color  steel  gray  to  grayish  black.  H.  =  3. 
Soluble  in  Aqua  Regia  only.  Its  insolubility  in  nitric 
acid  is  the  best  means  of  distinguishing  it  from  chalco- 
cite. 

Pyrite.  —  Its  pale  brass  yellow  color  is  one  of  the  best 
means  of  identification.  On  account  of  its  hardness,  it 
retains  scratches  long  after  the  other  constituents.  H.  =  6 
-  6.5.  Etched  by  nitric  acid. 

*  Probably  because  in  the  Sudbury  ores,  magnetite  is  present  in  small  grains  in  a 
softer  matrix. 


QLO 


OF  THE  OPAQUE   MINERALS  7 

These  colors  were  apparently  taken  by  Simpson  from  the 
descriptions  in  a  text-book  on  mineralogy,  and  do  not  in  all  cases 
represent  the  colors  on  the  polished  surface. 

-  Warren44  described  briefly  the  appearance  of  magnetite  and 
ilmenite  (in  titaniferous  magne.tite)  etched  by  strong  HC1,  and 
unetched,  saying  that  the  ilmehite  appeared  as  bright  gray,  narrow 
strips,  and  the  magnetite  as  duff  black. 

-  Koenigsberger22  devised  a  method  for  observing  the  optical 
character  of  opaque  minerals  in  reflected  light.     He  used  a  re- 
flecting prism  for  a  vertical  illuminator,  and  employed  a  Savart 
plate  of  calcite,  a  movable  plate  of  plane  glass  and  one  nicol. 
The  magnification  recommended  was  about  100  diameters.     The 
apparatus  was  adjusted  with  an  isotropic  metallic  mirror  so  that 
the  Savart  bands  were  not  visible  when  the  glass  plate  was  hori- 
zontal, but  appeared  when  this  was  rotated  vertically  through 
a   large   angle.     Isotropic   minerals   behave  like   the   glass,   but 
anisotropic  minerals  show  the  Savart  bands,  with  four  positions  of 
extinction  and  four  of  greatest  brightness,  as  the  stage  is  rotated. 
His  claims  are  as  follows:    He  could  distinguish  the  relation  be- 
tween optic  and  crystal  symmetry  by  means  of  a  contrast  plate 
attached  in  front  of  the  prism  illuminator.     By  the  determina- 
tion of  extinction  angles  on  oriented  sections,  he  could  discriminate 
between  monoclinic  and  orthorhombic  minerals.     If  a  mineral  is 
weakly  anisotropic,  it  may  be  confused  with  isotropic  minerals. 
Some  minerals  are  isotropic  for  one  color  of  light,  and  not  for 
another.     He  could  tell  whether  or  not  symmetry  is  reached  by 
hidden  twinning.     When  crystal  faces  are  not  available,  isotropism 
or  anisotropism  can  be  determined  more  easily  this  way  than  by 
study  of  any  physical  properties.     He  found  that  a  basal  plate 
of  molybdenite  was  isotropic.     Hematite,  pyrite,  chromite,  frank- 
linite,  argentite  and  tetrahedrite  are  also  isotropic  on  basal  sec- 
tions.    Pyrrhotite,  parallel  to  the  base,  is  made  up   of   feebly 
anisotropic  parts.     Glaucodot  is  feebly  anisotropic  perpendicular 
to  the  vertical  axis;  chalcopyrite  is  strongly  anisotropic.     Chalco- 
cite  is  isotropic  on  the  base.     Manganite,  columbite,  hematite  and 
ilmenite  are  quite  strongly  anisotropic. 

For  a  fuller  description  of  Koenigsberger 's  apparatus  and 
methods  the  reader  is  referred  to  his  paper,22  or  the  translated 
abstract  in  Winchell's  Optical  Mineralogy.46  He  laid  great  stress 
on  the  necessity  of  very  careful  and  perfect  polish,  and  recom- 


8  MICROSCOPICAL   DETERMINATION 

mended  chrome  oxide  for  the  final  polish.  Little  success  appears 
to  have  attended  the  trial  of  this  method  in  this  country  and  the 
validity  of  some  of  his  premises  is  not  universally  accepted. 

191  i.  —  Laney24  etched  chalcocite  with  nitric  acid,  and  devel- 
oped cleavages  in  it,  which  he  suggested  were  prismatic  and  basal. 
—  Lee26  investigated  a  number  of  minerals  on  the  polished  surface, 
and  gave  an  elaborate  table  of  tarnish  colors  and  coatings  formed 
by  various  reagents.  His  plan  involved  etching  the  whole  speci- 
men, and  moreover  it  appears  that  he  was  unable  to  secure  a  good 
polish  on  his  minerals,  so  that  the  difficulty  of  identification, 
especially  of  small  areas,  seems  too  great  for  practical  use  of  his 
methods.  Below  is  given  a  list  of  the  minerals  studied  by  Leo. 

Pyrrhotite  Pyrite  Barnhardtite  [mixture] 

Pentlandite  Marcasite  Linnaeite 

Millerite  Bornite  Cubanite  [mixture] 

Horbachite  Chalcopyrite  Polydymite 

-  Lincoln27  gave  a  valuable  table  for  the  identification  of  gold 
minerals  and  some  associated  minerals.     This  table  is  reproduced 
on  the  following  page. 

1912.  —  Bastin2  mentioned  galena,  chalcopyrite,  sphalerite, 
pyrite,  polybasite,  proustite  and  stephanite,  but  does  not  give 
determinative  criteria  for  all.  He  noted  the  triangular  pits  in 
galena,  and  gave  the  following  characteristics  of  polybasite. 
"  The  freshly  polished  surface  (of  polybasite)  has  much  the  ap- 
pearance of  chalcocite  .  .  .  but  unlike  chalcocite  it  does  not 
tarnish  or  etch  readily  when  treated  with  HN03.  When  treated 
with  concentrated  HN03,  a  tarnish  begins  to  appear  on  this 
mineral  at  about  the  same  time  that  it  appears  on  the  chalcopyrite 
of  the  ore.  When  the  chalcopyrite  shows  a  faint  peacock  tarnish 
the  polybasite  exhibits  a  yellowish  brown  color,  in  places  showing 
slight  iridescence.  In  specimens  where  the  polybasite  is  present 
in  too  small  amounts  to  be  isolated,  it  may  be  identified  in  the 
polished  section  by  this  characteristic  behavior  with  HN03." 

-  Singewald38  said  that  on  the  polished  surface  etched  with  hot 
HC1,  ilmenite  appears  bright  and  unaltered,  and  magnetite  is  some- 
what dull  black. 

-Brunton10  described  the  same  minerals  as  Singewald.  He 
could  see  no  difference  on  the  unetched  surface  between  ilmenite  and 
magnetite.  He  also  polished  rutile,  and  said  it  has  a  reddish  tinge. 


OLO 


OF  THE  OPAQUE   MINERALS 


I 


3 


§ 


0 

fl 
•""»   c3  ^^  ^2        C5        C^  ^5 

O        O        O  '      O        O 

as 

r. 

f  '  / 

43       43       43 

CO            02            OS 

o 

o     oo     o  <   oo 

O        O         ^^^^^^ 

w 

0| 

f->    •*-*      fcH    -1"3      ^    •*•* 

coo 

£ 

3 

<* 

oW^3 

fl              rt 

0        00        0       00 

o      o      o      o       g-- 

o 

1 

II 

PQ 

1 

§   §   § 

te 

42        42        42 

*?. 

o      o     .2     .20  » 

|«l°        lUfll 

0 

S     S         W 

n                 PQ       PQ       pQ 

0)          0)          OJ 

- 

333 

1-1 

_      _      .cc      .2  — 

02            00            02  °^    GO  °^5    GO  °^    O3 

O 

flNl3         flSfiCGCc 

W 

I5I"  1 

^O^g^O^O^O^ 

bfl       bC 

2 

1     1    | 

• 

-s 

£       43-       ^       2-5 

43       43       43       43       43 

S 

I  if  1  si 

8     8     §     §     § 
s    s    a    a    a 

CO       PnCC       CO       >CO 

CO       CO       CO       CO       CO 

^O 

>> 

g 

1  ll  1  ll 

* 

^o 

%•      &«       »       oo 

J>i         03          QJ          QJ          Oj 

o      .t2      .t2      .-S      .t2 

s 

1  12  2  2S 

1  1  ^  i  1 

& 

. 

.2   . 

^^ 

£* 

t> 

I 

S 

3     '^  •      «     ^^ 

I  t*  1  11 

-5        cTS        ^        ^^ 
o3       43  >>      ,            >i  cj 
J5       OfC      S       1^0 

C3         -2                         I 

1  1  5  a  1 

>         bC        N         M         ^ 

"^        rt        "^         m       "3 

Other  commor 
minerals  .  .  . 

10  MICROSCOPICAL  DETERMINATION 

1913.  —  Graton  and  Murdoch17  gave  a  brief  account  of  the  sig- 
nificance of  the  commoner  sulphides  in  ores  of  copper,  with  no 
attempt    to   give   other   determinative    characteristics   than   are 
implied  by  manner  of  occurrence. 

1914.  —  Thompson41  described  the  appearance  of  the  following 
minerals. 

Chalcopyrite,  smooth,  bright  brass  color. 
Pyrrhotite,  generally  pitted,  distinctive  light  bronze. 
Galena,  dazzling  white. 
Sphalerite,  smooth,  blue. 
Chalcocite,  etched  by  nitric  acid. 

Tetrahedrite  ]  ... 

\  no  criteria  given. 
Bornite          j 

-Bruce9  has  assembled  a  number  of  tests  made  by  pre- 
vious investigators,  and  has  added  a  considerable  number  made 
by  himself.  In  addition  he  gave  brief  notes  on  manipulation 
and  chemical  tests,  and  listed  a  few  reactions  for  elements,  as 
follows : 

Iron.  —  Fresh  K4Fe(CN)6  +  acid  gives  deep  blue. 

Nickel.  —  First  a  mixture  of  HNO3  and  tartaric  acid  is  applied, 
and  allowed  to  evaporate,  then  touched  with  a  drop  of  dimethyl- 
glyoxime,  freshly  made  ammoniacal,  which  gives  a  brilliant  red. 

Copper.  —  A  mixture  of  HNO3  and  K4Fe(CN)6  gives  a  deep  red. 
With  iron  present,  also,  this  is  followed  by  green. 

Manganese.  —  Most  manganese  minerals  are  soluble  in  HC1, 
giving  a  deep  brown  solution,  which  is  rendered  colorless  by 
addition  of  H202. 

Silver.  —  First  HNO3,  which  is  allowed  to  evaporate,  then  is 
touched  with  HC1,  giving  a  white  precipitate.  Lead  and  mercury 
minerals  give  the  same. 

Bismuth.  —  First  HN03,  evaporated,  then  HC1  added.  Then 
water  is  added,  producing  a  white  precipitate. 

Bruce's  table  of  tests  is  given  below. 

I.   MINERAL  BY  INCLINED  ILLUMINATION  is  YELLOW. 

A.  Etched  by  HC1. 

Pyrrhotite.  —  Bronze   yellow.     Surface  rough.     Reacts  for   Fe. 

B.  Etched  by  HN03,  not  by  HC1. 

(a)    Without  noticeable  tarnish  or  deposit. 
Pyrite.  —  Pale  yellow.     Slightly  rough.     Reacts  for  Fe. 


OF  THE  OPAQUE  MINERALS  11 

Marcasite.  —  Pale  yellow.     Slightly  rough.     Reacts  for  Fe. 

Precipitates  Ag  (?). 

Millerite.  —  Slightly  rough*.     Reacts  for  Ni. 
(6)    With  tarnish. 
Chalcopyrite.  —  Deep  yellow.     Rough.     Reacts  for  Fe  and  Cu. 

Iridescent  tarnish. 
C.     Not  attacked  by  single  acids. 

Gold.  —  Deep  yellow.     Smooth.     Amalgamates  with  Hg. 

II.    MINERAL  is  WHITE 

A.  Etched  by  HC1. 

B.  Etched  by  HN03. 

(a)    With  no  tarnish  or  deposit. 

Smaltite.  —  Rough  with  bright  facets.     Gives  Ni  test. 

Arsenopyrite.  —  Rough  with  bright  facets.  Becomes  gray  with 
reddish  spots.  —  Reacts  for  Fe,  not  for  Ni. 

Leucopyrite.*  —  White.     Very  rough.     Reacts  for  Fe. 

Silver.  —  Smooth.     Reacts  for  Ag. 

Bismuth.  —  Smooth.     Reacts  for  Bi. 
(6)    With  deposit. 

Arsenic.  —  Chalky  white  deposit. 

Antimony.  —  Chalky  white  deposit. 

C.  Unattacked  by  single  cold  acids. 

Cobaltite.  —  Slightly  rough.     Etched  by  HNO3. 
Niccolite.  —  Slightly  rough  with  reddish  tinge.     Treated  with 
Aqua  Regia  reacts  for  Ni. 

III.     MINERAL  is  BLACK  OR  GRAYISH  BLACK 

A.     Etched  by  HC1. 

Magnetite.  —  Shows  intersecting  parting  planes.  Etches  easily. 
Fe  reaction. 

Franklinite.  —  Fairly  smooth.  Etches  less  readily  than  mag- 
netite. 

Ilmenite.  —  Fairly  smooth.     Etches  very  slowly. 

Hematite.  —  Steel  gray.     Smooth.     Red  streak. 

Manganite.  —  Dull  black.     Brown  solution. 

Psilomelane.  —  Brown  and  black  areas.     Brown  solution. 

Braunite.  —  Black.     Etches  to  bluish  black.     Brown  solution. 

*  Same  as  lollingite. 


12  MICROSCOPICAL  DETERMINATION 

Alabandite.  —  Smooth,  grayish  black.      Very  easily  attacked. 

(40  sec.) 
Pyrolusite.  —  Black  fibrous  surface.     Soft.     Brown  solution. 

B.  Etched  by  HNO3,  not  by  HC1. 
(a)    Without  tarnish. 

Enargite.  —  Dull  grayish  black.     Etches  to  fibrous  structure. 
Cu  test. 

Argentite.  —  Smooth  dull  black.     Ag  test.     Sectile. 

Stephanite.  —  Smooth  dull  black.     Ag  test. 
(6)    With  a  tarnish. 

Chalcocite.  —  Smooth    black.      Etched   to   a   bluish   tarnish, 
later  becoming  peacock  colors. 

Bornite.  —  Pitted.     Purple  color.    Etches  to  a  peacock  tarnish. 

Reacts  for  both  Fe  and  Cu. 
(c)    With  a  deposit. 

Galena.  —  Smooth  black.     Etches  easily,  with  a  yellow  de- 
posit. 

Bournonite.  —  Smooth  dull  black.     Etches  easily,  with  yel- 
lowish opalescent  deposit.     Cu  test. 

Stibnite.  —  Smooth   dull   black.      Etches   fairly  slowly   to   a 
fibrous  structure  with  a  chalky  deposit. 

Tetrahedrite.  —  Smooth.     Bluish  black.     Etches  with  an  opal- 
escent deposit.     Reacts  for  copper. 

C.  Unattacked  by  single  acids. 
Molybdenite. 

Chromite. 

Cassiterite.  —  Black  deposit  by  electric  etching. 

Columbite. 

This  paper,  dealing  with  37  species,  is  the  most  extensive  so 
far  published  on  opaque  mineral  identification,  and  is  intended 
as  a  summary  of  results  up  to  date.  In  etching,  Bruce  used  con- 
centrated acids  for  periods  of  several  minutes,  so  that  the  reactions 
are  in  many  cases  quite  different  from  those  produced  by  the 
more  dilute  reagents  and  shorter  time  of  etching  advocated  in 
the  present  book.  It  is  not  clear,  however,  why  oblique  illumi- 
nation alone  has  been  employed  for  Bruce's  determinations. 
This  has  been  found  of  considerable  service  in  examining  trans- 
parent sulphides,  like  sphalerite  or  ruby  silver,  but  this  result 
may  easily  be  obtained  by  cutting  off  the  vertical  illumination 
temporarily.  Experience  has  indicated  that  vertical  illumination 


OF  THE  OPAQUE   MINERALS  13 

is  more  effective  in  the  case  of  opaque  minerals,  since  the  per- 
fectly smooth  surface  of  any  opaque  substance,  regardless  of  its 
real  color,  will  appear  black,  or  nearly  so,  with  oblique  light, 
except  with  very  low  powers;  and  a  rough  surface,  which  alone 
will  show  the  true  color  of  tha  mineral  by  inclined  illumination, 
is  extremely  undesirable  from*  many  standpoints. 

-  Rogers44  stated  that  magnetite  has  a  rough  surface ;  hematite 
is  rather  smooth,  faintly  scratched;  bornite  and  chalcopyrite  are 
easily  recognized  by  their  colors.  He  also  said  that  with  plane 
polarized  light,  covellite  shows  pleochroism,  deep  blue  (parallel 
to  the  plane  of  vibration  of  the  nicol)  to  light  blue  (perpendicular 
to  this). 

-Kraus  and  Goldsberry23  examined  polished  bornite  crystals 
to  ascertain  their  purity,  and  analyzed  material  from  the  same 
crystals,  but  gave  no  determinative  criteria  for  identifying  this 
mineral. 

1915.  —  Chamot15  published  a  valuable  book  on  microchemistry, 
giving  microchemical  tests  for  the  elements,  manipulation,  etc., 
and  methods  of  polishing,  intended  especially  for  metals  and 
alloys,  but  applicable  to  a  great  extent  to  opaque  minerals  as 
well. 

—  Thompson43  mentioned  the  following  minerals  but  gave  no 
criteria  for  their  identification:  Pyrite,  chalcocite,  bornite,  chal- 
copyrite, covellite,  enargite,  sphalerite,  tetrahedrite  and  a  white 
alteration  product  of  enargite.  Following  earlier  work  by  others, 
he  etched  covellite  and  enargite  with  KCN  and  stated  that  it 
developed  a  structure  in  them. 

From  this  summary  it  is  evident  that  a  considerable  number 
of  the  commoner  and  some  of  the  rarer  opaque  minerals  have 
been  studied  and  described,  and  in  addition  undoubtedly  much 
valuable  work  of  this  nature  has  been  done,  but  not  yet  pub- 
lished. Nevertheless,  no  systematic  attempt  appears  to  have 
been  made  to  cover  the  whole  field  of  the  opaque  minerals,  and 
little  attention  has  been  paid  to  standardization  of  methods,  many 
of  which  appear  to  have  been  developed  without  regard  to  previous 
work.  In  consequence,  much  effort  has  been  wasted  in  duplica- 
tion, and  variable  results  have  often  been  obtained,  while  most  of 
the  opaque  minerals  have  been  left  without  means  of  determination 
by  the  microscopic  method. 


14  MICROSCOPICAL  DETERMINATION 

SCOPE  OF  PRESENT  WORK 

In  1911,  a  mineralographic  investigation  of  some  of  the  sulphide 
ores  of  copper  was  undertaken  by  L.  C.  Graton  and  the  author.17 
It  was  at  once  seen  to  be  very  essential  to  know  what  the  differ- 
ent ore  minerals  looked  like,  and  how  they  behaved  chemically, 
under  the  microscope.  Accordingly,  many  previously  deter- 
mined specimens  of  the  commoner  opaque  minerals  were  assembled 
and  studied,  and  thus  it  was  possible  to  reduce  materially  the 
uncertainties  in  determination,  and  often  in  interpretation  of 
structure.  The  author  has  continued  the  determinative  part 
of  this  work  in  the  laboratory  of  Mining  Geology  of  Harvard 
University,  and  the  present  book  is  the  result  of  investigations 
carried  on  over  a  period  of  nearly  four  years.  It  does  not  discuss 
the  paragenesis  or  significance  of  the  minerals  and  structures 
involved.  The  great  importance  of  these  problems  is  evident, 
but  this  book  has  been  strictly  confined  to  mineral  identification. 
It  is  devoted  solely  to  determination  of  the  physical  and  chemical 
properties  of  the  opaque  minerals,  as  observed  under  the  micro- 
scope, with  a  classification  of  these  data  in  such  form  as  to  permit 
their  ready  application  to  problems  of  identification,  somewhat 
after  the  manner  of  Brush  and  Penfield's  or  Johannsen's  deter- 
minative tables.  The  primary  object  has  been  the  production  of  a 
practical  and  simple  scheme  of  mineral  identification,  and  accord- 
ingly only  those  lines  of  investigation  have  been  pursued  which 
contributed  directly  toward  this  end.  Further  work  will  probably 
modify  some  of  the  results  attained,  especially  when  extended  to 
additional  associations  of  minerals  and  to  sub-species  and  varia- 
tions not  yet  studied.  The  methods  of  investigation  will  also 
doubtless  be  improved,  b.ut  the  present  results  have  been  found 
to  afford  a  practical  means  of  mineral  determination  and  may 
serve  as  a  ground  work  for  future  research  in  a  field  that  promises 
to  be  of  great  importance.  In  a  work  dealing  with  so  new  a  field, 
however,  errors  and  omissions  are  likely  to  be  found,  and  notice  of 
any  such  will  be  much  appreciated. 

The  collection  studied  includes  186  definite  minerals,  a  few  of 
which  are  as  yet  unidentified,  or  perhaps  new;  a  few  mixtures, 
with  known  and  with  unknown  constituents,  which  have  been 
previously  regarded  as  true  minerals,  and  as  such  have  been  given 
mineral  names ;  and  some  definite  varieties  of  known  species,  such 
as  the  argentiferous  tetrahedrite,  freibergite.  The  minerals  have 


OF  THE  OPAQUE   MINERALS  15 

been  assembled  from  the  collections  of  various  mineralogical  mu- 
seums, with  some  from  private  collections  and  mineral  dealers. 
The  list  comprises  a  few  metallic  elements  and  oxides,  and  prac- 
tically all  the  minerals  of  the  sulphide  and  sulpho-salt  groups,  in- 
cluding selenides,  tellurides  and  arsenides.  A  few,  like  cuprite  or 
the  ruby  silvers,  are  transparent,  but  are  included  because  of  their 
character  and  associatiens.  Tfiere  are  a  number  of  named  species 
not  represented,  but  only  a  few  of  these  are  true  minerals,  most  of 
them  being  admittedly  mixtures,  or  very  dubious. 

In  the  case  of  each  mineral,  specimens  from  two  or  more  local- 
ities have  been  secured  and  studied,  whenever  possible,  as  a 
check  on  the  uniformity  of  the  findings,  and  specimens  previously 
determined  by  chemical  or  crystallographic  methods  have  been 
given  preference  in  every  instance.  Nevertheless,  many  species 
are  represented  by  but  a  single  specimen,  and  in  order  that  the 
reader  may  judge  of  the  reliability  of  the  determination,  the 
number  of  localities  from  which  specimens  have  been  secured 
and  studied  has  been  put  in  parentheses  after  each  mineral 
name  in  the  Index  of  Minerals,  (n)  indicates  more  than  five 
localities.  When  only  one  specimen  was  available,  or  when  the 
mineral  is  dubious,  a  letter  or  symbol  is  added  to  indicate  the 
value  of  the  description.  Thus:  G  =  Reliable.  F  =  Probably 
reliable.  ?  =  Doubtful.  For  example,  there  is  only  one  specimen 
of  glaucodot  in  the  collection,  but  it  is  a  large  crystal,  definitely 
identified.  This,  of  course,  increases  the  value  of  the  observa- 
tions on  this  mineral,  but  does  not  assure  that  its  properties  would 
be  constant  in  different  localities.  It  has  been  found,  however, 
that  specimens  of  the  same  mineral  from  different  localities 
usually  correspond  very  closely.  For  the  commoner  minerals, 
especially,  this  fact  has  been  established  by  observations  on  hun- 
dreds of  specimens  of  ore  from  various  parts  of  the  world. 

The  author  wishes  especially  to  express  his  indebtedness  to 
Professor  L.  C.  Graton,  of  Harvard  University,  for  much  valuable 
advice  and  helpful  criticism  throughout  this  work,  and  for  sup- 
plying much  material  of  great  value  to  the  study.  Professor 
J.  E.  Wolff  and  Professor  Charles  Palache,  of  Harvard  University, 
have  very  kindly  furnished  much  material  from  the  Museum 
Collections,  and  have  given  information  that  has  been  of  great 
assistance.  Professor  Waldemar  Lindgren,  of  the  Massachu- 
setts Institute  of  Technology,  has  been  kind  enough  to  give  this 


16  MICROSCOPICAL  DETERMINATION 

work,  in  manuscript  form,  a  practical  trial  and  to  offer  valuable 
suggestions.  To  the  generosity  of  Mr.  W.  A.  Roebling  of  Trenton, 
N.  J.,  is  due  the  opportunity  to  study  many  very  rare  and  valuable 
specimens  of  his  collection,  thereby  adding  greatly  to  the  complete- 
ness of  the  work.  Much  valuable  material  has  been  obtained 
through  the  courtesy  and  generosity  of  Drs.  G.  P.  Merrill  and 
J.  E.  Pogue  of  the  National  Museum  at  Washington;  Professor 
W.  E.  Ford  of  Yale  University;  and  Dr.  L.  P.  Gratacap  of  the 
American  Museum  of  Natural  History,  N.  Y.,  to  whom  grateful 
acknowledgment  is  made.  The  spirit  which  has  led  numerous 
practicing  geologists  and  engineers  to  transmit  interesting  and 
unusual  materials  from  many  parts  of  the  world  is  also  much 
appreciated. 

BIBLIOGRAPHY 

The  following  list  includes  the  titles  of  all  papers  known  to 
the  author,  in  which  use  has  been  made  of  mineralography  whether 
dealing  directly  with  mineral  identification  or  not,  or  which  have 
been  referred  to  in  preparing  this  work;  it  may  be  regarded  as 
fairly  complete.  The  papers  are  referred  to  by  number  in  the 
text. 

1.  ALLEN,  E.  T.     Private  communication. 

2.  BASTIN,  E.  S.     Metasomatism  in  downward  sulphide  enrichment.     Econ. 

Geology,  Vol.  VIII,  1912,  p.  51. 

3.  -     -  Geology  of  the  pitchblende  ores  of  Colorado.    U.  S.  Geol.  Survey, 

Prof.  Paper  90-A,  1914. 

4.  BAUMHAUER,  H.     Ueber  die  mikroskopische  Beschaffenheit  eines  Bunt- 

kupfererzes  von  Chloride  (New  Mexico).     Zeitschr.  fiirKryst.,  etc.,  Vol. 
10,  1885,  p.  447. 

5.  BEIJERINCK,  F.     Ueber  das  Leitungsvermogen  der  Mineralien  fiir  Elektri- 

citat  Jahrb.  fiir  Min.,  etc.,  Beilage  Band  11,  1897-8,  pp.  403-474. 

6.  BERZELIUS,  J.  J.     [note]  Gilb.  Ann.,  Vol.  XLVIII,  1814,  p.  209. 

7.  BEYSCHLAG,  VOGT  and  KRUSCH.     Ore  deposits,  Vol.  I.    Translated  by  S.  J. 

Truscott,  London,  1914  (original,  1909). 

8.  BOYLE,  A.  C.,  JR.     Geology  and  ore  deposits  of  the  Bully  Hill  mining  dis- 

trict, California.    Am.  Inst.  Min.  Eng.,  Trans.,  Vol.  XLVIII,  1914,  pp. 
67-114. 

9.  BRUCE,  E.  L.     Microscopic  tests  on  opaque  minerals.     School  of  Mines 

Quarterly,  Vol.  35,  1914,  p.  187. 

10.  BRUNTON,   S.     Some   notes   on   titaniferous  magnetite.     Econ.    Geology, 

Vol.  VII,  1912,  p.  670. 

11.  BUTLER,  B.  S.    Geology  and  ore  deposits  of  the  San  Francisco  region, 

Utah.    U.  S.  Geol.  Survey,  Prof.  Paper  80,  1913. 


OF  THE  OPAQUE  MINERALS  17 

12.  CAMPBELL,  W.    The  microscopic  examination  of  opaque  minerals.    Econ. 

Geology,  Vol.  I,  1906,  p.  751. 

13.   and  KNIGHT,  C.  W.    A  microscopic  examination  of  the  cobalt  nickel 

arsenides  and  silver  deposits  of  Temiskaming.    Econ.  Geology,  Vol.  I, 
1906,  p.  767. 

14. The  microstructure  ol  nickeliferous  pyrrhotite.    Econ.  Geology, 

Vol.  II,  1907,  p.  350. 

15.  CHAMOT,  E.  M.    Elementary  chefcnical  microscopy.     New  York,  1915. 

16.  FINLAYSON,  A.  M.    The  pyritic  deposits  of  Huelva,  Spain.     Econ.  Geol- 

ogy, Vol.  V,  1910,  pp.  357  and  403. 

17.  GRATON,  L.  C.  and  MURDOCH,  J.    The  sulphide  ores  of  copper;   some  re- 

sults of  microscopic  study.    Am.  Inst.  Min.  Eng.,  Trans.,  May,  1913, 
p.  741. 

18.  HARRINGTON,  B.  J.    On  the  formula  of  bornite.    Am.  Jour.  Sci.,  4th  series, 

Vol.  16,  1903,  p.  151. 

19.  HUSSAK,  E.     Ueber  die  Mikrostruktur  einiger  Brasilianischer  Titanmag- 

neteisensteine.     Neues  Jahrb.  fur  Min.,  etc.,  Vol.  I,  1904,  p.  94. 

20.  JOHANNSEN,  A.     Manual  of  petrographic  methods.     New  York,  1914,  p.  572. 

21.  JULIEN,  A.  A.     On  the  variation  of  decomposition  of  the  iron  pyrites,  its 

cause  and  relation  to  density.    Ann.  N.  Y.  Acad.  Sci.,  Vol.  IV,  1885, 
p.  141. 

22.  KOENIGSBERGER,  J.     Ueber  einen  Apparat  zur  Erkennung  und  Messung 

optischer  Anisotropie  undurchsichtiger  Substanzen  und  dessen  Verwen- 
dung.     Centralblatt  fur  Min.,  etc.,  1908,  pp.  565,  597. 

23.  KRAUS,  E.  H.  and  GOLDSBERRY,  J.  P.    The  chemical  composition  of  born- 

ite and  its  relation  to  other  sulpho-salts.    Am.  Jour.  Sci.,  4th  series,  Vol. 
37,  1914,  p.  539. 

24.  LANEY,  F.  B.     The  relation  of  bornite  and  chalcocite  in  the  copper  ores  of 

the  Virgilina  district  of  North  Carolina  and  Virginia.     Econ.  Geology, 
Vol.  VI,  1911,  p.  399. 

25.  LEE,  M.  L.    A  geologic  study  of  the  Elisa  mine,  Sonora,  Mexico.    Econ. 

Geology,  Vol.  VII,  1912,  p.  324. 

26.  LEO,  M.    Die  Anlauffarben.     Dresden,  1911. 

27.  LINCOLN,  F.  C.     Certain  natural  associations  of  gold.     Econ.  Geology, 

Vol.  VI,  1911,  p.  247. 

28.  LINDGREN,  W.     Mineral  deposits.     New  York,  1913. 

29.   and  WHITEHEAD,  W.  L.    A  deposit  of  jamesonite  near  Zimapan, 

Mexico.     Econ.  Geology,  Vol.  IX,  1914,  p.  435. 

30.  RANSOME,  F.  L.     Copper  deposits  near  Superior,  Arizona.    U.  S.  Geol. 

Survey.,  Bull.  540,  Part  I,  1914,  p.  139. 

31.  RAY,  J.  C.    The  reflecting  microscope  in  mining  geology  and  metallurgy. 

Min.  &  Sci.  Press,  June,  1914,  p.  922. 

32.  -     -  Paragenesis  of  the  ore  minerals  in  the  Butte  district,  Montana.     Econ. 

Geology,  Vol.  IX,  1914,  p.  463. 

33.  RIDGWAY,  R.     Color  standards  and  nomenclature.     Olney,  111.,  1912. 

34.  ROGERS,  A.  F.    Upward   secondary  sulphide   enrichment   and  chalcocite 

formation  at  Butte,  Montana.     Econ.  Geology,  Vol.  VIII,  1913,  p.  781. 


18  MICROSCOPICAL  DETERMINATION 

35.  Secondary  sulphide  enrichment  of  copper  ores  with  special  reference 

to  microscopic  study.  Min.  &  Sci.  Press,  October,  1914,  p.  681. 

36..  -  The  chemical  composition  of  bornite.  Science,  new  series,  Vol. 
XLII,  1915,  p.  386. 

37.  SIMPSON,  J.  F.    The  relation  of  copper  to  pyrite  in  the  lean  copper  ores  of 

Butte,  Montana.     Econ.  Geology,  Vol.  Ill,  1908,  p.  628. 

38.  SINGEWALD,  J.  T.     Microstructure  of  titaniferous  magnetite.    Econ.  Geol- 

ogy, Vol.  VIII,  1913,  p.  207. 

39.  -  The  titaniferous  magnetites  of  the  United  States,  U.  S.  Bureau  of 

Mines,  Bull.  64,  1913. 

40.  SORBY,  H.  C.     On  the  microscopic  structure  of  the  calcareous  grits  of  the 

Yorkshire  coast.    Quart.  Jour.  Geol.  Soc.,  Vol.  VII,  1851,  pp.  1-6. 

41.  -  Preparation  of  transparent  sections  of  rocks  and  minerals.     Northern 

Microscopist,  Vol.  II,  1828,  pp.  101-106,  133-140. 

42.  THOMPSON,  A.  P.    The  relation  of  pyrrhotite  to  chalcopyrite  and  other 

sulphides.     Econ.  Geology,  Vol.  IX,  1914,  p.  153. 

43.  -  The  occurrence  of  covellite  at  Butte,  Montana.    Am.  Inst.  Min.  Eng., 

Bull.  100,  April,  1915,  p.  645. 

44.  TURNER,  H.  W.  and  ROGERS,  A.  F.    A  geologic  and  microscopic  study  of  a 

magmatic  copper  sulphide  deposit  in  Plumas  County,  California,  and  its 
modification  by  ascending  secondary  enrichment.  Econ.  Geology,  Vol. 
IX,  1914,  p.  359. 

45.  WARREN,  C.  H.    Petrography  and  mineralogy  of  Iron  Mine  Hill,  Cumber- 

land, R.  I.    Am.  Jour.  Sci.,  4th  series,  Vol.  25,  1908,  p.  15. 

46.  WINCHELL,  N.  H.  and  WINCHELL,  A.  N.     Elements  of  optical  mineralogy. 

2d  Appendix.     New  York,  1909. 

47.  BERG,  G.  Mikroskopische  Untersuchung  der  Erzlagerstatten.    Berlin,  1915. 

(This  came  to  hand  too  late  for  more  than  a  brief  note.  Berg  has  classified 
a  number  of  the  commoner  ore  minerals  by  their  appearance  in  reflected 
light  (in  thin  sections)  and  by  their  different  microchemical  behavior. 
He  apparently  has  not  used  polished  sections.) 


TECHNIQUE  OF  MINERALOGRAPHY 

P(OLISfflNG 

The  mineral  to  be  examined  %hould  be  polished  so  that  it  has 
rather  large  areas  shiny,  or  very  smooth,  and  free  from  pits,  and 
should  have  few  or  no  scratches.  This  relatively  perfect  polish 
is  necessary  in  this  work,  as  a  much  pitted  or  scratched  surface 
often  obscures  the  true  color  of  a  mineral,  and  may  even  modify 
somewhat  the  microchemical  reactions.  For  example,  some  of 
the  hard  minerals,  like  hematite  or  magnetite,  appear  gray  instead 
of  white,  if  the  surface  has  not  at  least  fair-sized  areas  free  from 
pits.  Minerals,  like  pyrite,  which  scratch  instead  of  pitting, 
should  not  be  polished  too  shiny  after  they  have  reached  a  con- 
dition permitting  identification,  as  this  would  develop  too  much 
relief  as  compared  with  adjacent  softer  minerals  —  a  thing  which 
is  not  desirable. 

Campbell12  and  Ray31  give  accounts  of  polishing  methods  for 
which  the  reader  is  referred  to  their  respective  papers.  Other 
workers  have  variations  of  their  own,  and  individual  preferences  will 
differ.  The  following  method  has  been  found  most  satisfactory 
in  the  opinion  of  the  author. 


FIG.  1.  —  Polishing  Apparatus. 

The  grinding  apparatus  used  is  Sauveur's  machine  for  polishing 
steel.  (See  Fig.  1.)  It  consists  of  a  horizontal  spindle  with  two 
vertical  iron  discs  8  inches  diameter  and  f  inch  thick,  run  at  about 

19 


20  MICROSCOPICAL  DETERMINATION 

1200  revolutions  per  minute.  This  gives  four  polishing  surfaces. 
The  first  is  a  J-inch  carborundum  wheel  laid  against  one  side  of 
the  first  iron  disc.  The  carborundum  wheel  that  gives  best 
results  is  a  mixture  of  40-,  60-  and  80-mesh  carborundum,  soft- 
bonded,  so  it  will  not  readily  clog  or  grow  dull.*  On  the  other 
side  of  the  first  disc  is  stretched  a  heavy  canvas  cover,  armed  with 
220-mesh  carborundum  powder,  mixed  with  water  to  a  thin  pasty 
consistency,  and  applied  to  the  revolving  wheel  with  a  flat  brush 
about  1|  inches  wide.  The  other  disc  is  covered  on  both  sides 
with  broadcloth,  to  which  is  similarly  applied  a  very  thin  paste  of 
tripoli  powder,  on  one  side,  and  of  rouge  on  the  other.  The  rouge 
and  tripoli  used  in  polishing  steel  are  quite  satisfactory  for  minerals, 
and  if  carborundum  powder  is  not  available,  flour  emery  instead 
may  be  used  on  the  canvas  wheel. 

Specimens  varying  in  size  from  over  two  inches  in  diameter 
down  to  the  smallest  piece  that  can  be  held  in  the  fingers  may  be 
handled  on  these  wheels.  Preferably,  the  rough  chips  are  about 
half  an  inch  to  an  inch  square  and  half  an  inch  thick,  and  with 
one  fairly  even  side  or  face  to  begin  with,  as  by  polishing  on  this 
face,  time  is  saved  in  the  grinding.  The  surface  may  be  most  rapidly 
flattened  by  pressing  it  diagonally  against  the  corner  of  the  carbo- 
rundum wheel,  before  applying  it  to  the  smooth  side  of  the  wheel. 

The  carborundum  wheel  is  generally  used  dry,  but  may  be  fed 
with  water  if  the  specimen  to  be  ground  is  brittle,  or  likely  to  be 
injured  by  heating.  In  either  case,  it  is  often  advisable  to  cool 
the  specimen  from  time  to  time  by  a  moment's  immersion  in 
water.  On  delicate  specimens,  a  diamond  saw  may  be  used 
instead  of  this  wheel,  but  for  general  work,  the  carborundum 
wheel  is  more  satisfactory  and  much  cheaper.  The  purpose  of 
the  carborundum  wheel  is  to  cut  a  flat  surface  preparatory  to  the 
real  polishing.  It  is  also  used  to  bevel  off  the  edge  of  the  ground 
face  all  the  way  around,  which  must  be  done  to  avoid  the  danger 
of  tearing  the  cloth  of  the  other  wheels  by  sharp  or  irregular  pro- 
jections. When  this  has  been  done,  the  specimen  and  the  hands 
are  carefully  rinsed,  to  remove  any  particles  of  carborundum  or 
loose  fragments  of  the  specimen,  and  this  procedure  is  repeated 
after  the  operation  on  each  wheel  has  been  completed  and  before 
passing  to  the  next  wheel. 

*  The  Carborundum  Company's  specifications  are  as  follows:  Grit  403;  Grade  M; 
Bond  B3. 


HITE/       COLOR 


OF  THE  OPAQUE   MINERALS  21 

Then  the  specimen  is  applied  to  the  canvas .  wheel,  which  is 
kept  wet  and  well  supplied  with  carborundum  powder.  Here  the 
pits  produced  by  the  coarse  wheel  are  ground  out,  and  the  harder 
minerals,  like  magnetite  or  pyrite,  are  given  practically  whatever 
polish  they  are  to  receive.  I^it'tle  or  no  relief  is  developed  here, 
and  the  wheel  is  very  valuable  Jor  producing  a  plane  surface  free 
from  pits.  Most  specimens  should  be  kept  here  longest,  so  as  to 
save  time  and  trouble  later  on.  Very  soft  or  brittle  specimens, 
like  massive  chalcocite,  should  be  started  on  this  wheel,  to  avoid 
"  burning  "  or  cracking  by  heat  on  the  carborundum  wheel.  Con- 
siderable pressure  may  be  applied  here,  but  it  is  desirable  that  this 
be  lessened  at  the  end  of  grinding,  to  make  the  scratches  less  deep. 

When  the  surface  is  plane  and  unpitted,  and  the  specimen 
and  hands  have  been  rinsed,  polishing  on  the  third,  or  tripoli, 
wheel  is  begun.  The  specimen  should  not  be  pressed  heavily, 
but  only  moderately,  against  this  wheel.  Here  the  softer  min- 
erals, such  as  chalcopyrite,  are  polished,  though  usually  with 
fine  scratches  still  visible.  This  wheel  also  develops  relief,  by 
attacking  the  softer  without  much  affecting  the  harder  constitu- 
ents. Too  great  relief  is  not  desirable,  as  the  hard  constituents 
would  then  stand  high  and  prevent  the  formation  of  a  flat  surface 
on  the  softer  ones,  which,  though  shiny,  would  then  appear  grooved 
and  uneven,  and  their  relationships  would  be  obscured.  More- 
over, these  hard  minerals,  if  projecting  prominently,  tear  the 
surface  of  the  cloth,  and  wear  it  out  very  rapidly.  All  these 
difficulties  are  avoided  by  removing  most  of  the  pits  on  the  canvas 
wheel,  and  not  polishing  too  long  or  too  hard  on  the  tripoli  wheel. 

When  the  softer  minerals  appear  smooth,  the  specimen  is  again 
rinsed,  and  transferred  to  the  last,  or  rouge,  wheel.  This  usually 
does  little  more  than  give  a  burnish  to  the  specimen,  but  in  the 
case  of  chalcocite,  or  a  similarly  soft  mineral,  considerable  polish- 
ing is  done  here,  and  the  scratches  from  the  tripoli  wheel  are 
removed.  This  final  burnish  is  very  important,  but  it  is  not  usually 
necessary  to  polish  on  this  wheel  more  than  five  or  ten  seconds. 
The  specimen  is  then  dried  by  wiping  thoroughly  with  a  soft 
cloth,  or  by  rinsing  in  alcohol  and  drying  in  an  air  blast,  as  any 
moisture  will  injure  the  surface  of  the  rouge  block,  to  which  the 
specimen  is  next  transferred  for  the  last  step  in  its  preparation. 
The  rouge  block  consists  of  a  piece  of  chamois  skin  stretched 
over  a  flat  block  of  wood  and  fed  with  a  little  dry  rouge.  On  this 


22  MICROSCOPICAL  DETERMINATION 

the  specimen  is  rubbed  briskly,  but  without  excessive  pressure, 
for  a  few  seconds,  to  give  it  a  final  burnish,  and  to  remove  any 
films  or  specks  of  dirt  that  may  have  adhered  to  the  surface.  The 
rouge  block  must  be  kept  free  from  all  grit  and  dirt,  as  this  would 
scratch  and  mar  the  surface  of  the  specimen.  It  should  be  kept 
covered,  except  when  in  actual  use,  and  all  mineral  or  dirt  frag- 
ments removed  by  brushing. 

After  a  moderate  amount  of  practice,  in  which  experience  is 
gained  as  to  the  appropriate  pressure  to  apply,  and  the  minimum 
of  time  required  to  produce  the  desired  effect,  an  average  specimen 
may  be  polished  in  six  or  seven  minutes. 

Specimens  too  small  to  be  held  in  the  fingers  may  be  polished 
by  first  mounting  them  in  partly  melted  sealing  wax,  and  a  flat 
surface  produced  before  the  wax  hardens  by  pressing  the  wax 
containing  the  chip,  face  down  on  a  wet  glass  plate,  or  by  laying 
the  piece  face  down  on  a  wet  glass  and  running  melted  wax  over 
it.  Then  the  wax  and  specimen  together  may  easily  be  polished. 
Of  course  it  is  not  to  be  put  on  the  dry  carborundum  wheel,  as 
the  heat  of  friction  would  melt  the  wax,  but  is  to  be  started  on  the 
canvas. 

For  polishing  powders,  or  small  grains  of  minerals,  the  following 
procedure  is  convenient.  A  flat  surface  of  sealing  wax  is  softened, 
and  the  powder  sprinkled  thickly  over  this.  It  may  be  pressed 
in  by  the  finger  while  the  wax  is  still  soft,  or  melted  in  by 
additional  heat.  Then  the  softened  surface  is  pressed  on  a  wet 
glass  plate,  so  as  to  produce  a  flat  surface,  which  is  polished 
in  the  ordinary  way,  except  that  in  the  case  of  fine  powders, 
the  tripoli  wheel  is  the  coarsest  one  used.  By  this  means,  al- 
most impalpable  powders  may  be  polished  and  studied,  and  it 
is  especially  valuable  for  the  examination  of  churn  drill  pulps, 
mill  tailings  or  concentrates,  powders  and  minute  fragments  of 
synthetic  minerals,  or  tiny  crystals  of  rare  minerals.  In  the  case 
of  crystals,  polishing  may  be  done  in  carefully  oriented  direc- 
tions, and  a  number  of  oriented  surfaces  may  be  polished  on 
a  single  piece.  Crystal-lined  vugs,  or  crusts  of  crystals,  may  be 
filled  with  melted  wax  and  polished  down  carefully  without 
destroying  either  the  crystals  or  their  arrangement  or  injuring  the 
polishing  wheels.  Fusible  alloys,  or  dental  enamel,  may  be  used 
instead  of  wax,  especially  for  mineral  grains  that  are  hard  and 
apt  to  tear  out  when  polished. 


H 


OLOR 


OF  THE   OPAQUE   MINERALS 


23 


The  method  of  polishing  outlined  above,  or  a  similar  one,  is 
very  desirable  as  a  time-  and  labor-saving  arrangement,  but  is  not 
absolutely  essential.  As  a  matter  of  fact,  even  at  a  remote  mine 
or  prospect,  satisfactory  polished  sections  may  be  secured  without 
an  excessive  expenditure  of  ti^tie,  with  nothing  more  elaborate 
than  a  file  or  two,  a  number  of  sheets  of  emery  paper  of  varying 
degrees  of  fineness,  a  strip  of  chamois  skin  and  a  little  rouge. 
If  a  grindstone  is  available,  of  course  much  time  can  be  saved  in 
preparing  a  flat  surface  on  the  ore  chips. 


Glass  plate 


Specimen      / 


Mounting  wax 


SIDE  VIEW 


TOP  VIEW 


FIG.  2.  —  Method  of  Mounting. 
MOUNTING 

Specimens  may  be  mounted  for  examination  on  the  stage  of  the 
microscope  in  any  one  of  a  number  of  ways  by  which  the  polished 
surface  is  held  perpendicular  to  the  axis  of  the  microscope.  It 
has  been  found  convenient  to  mount  the  specimen,  by  means  of  a 
lump  of  modeling  wax,  on  a  metal  plate  3  inches  long,  1  inch  wide 
and  J  inch  thick.  The  polished  surface  is  made  parallel  to  the 
bottom  of  the  mount  by  pressing  it  down  with  a  piece  of  plate 
glass  until  this  rests  on  the  top  of  a  metal  ring  of  uniform  height, 
conveniently  about  f  inch,  which  is  placed  temporarily  on  the 
steel  plate  and  around  the  specimen.  (See  Fig.  2.)  This  is  a 
modification  of  Campbell's  cup  method.  The  mounted  specimen 
may  then  be  placed  on  the  microscope  stage  without  need  of 
further  adjustment.  To  permit  chemical  and  physical  tests  on 
the  polished  surface  directly  under  the  microscope,  a  type  of  in- 
strument that  holds  the  specimen  with  the  polished  surface  upward 
should  be  used,  but  for  other  purposes,  instruments  employing  in- 
verted mounting  are  as  satisfactory. 


24 


MICROSCOPICAL  DETERMINATION 


EXAMINATION 

For  the  microscopic  examination  of  polished  surfaces  of  opaque 
minerals,  an  ordinary  metallographic  microscope  is  used.  This 
carries  a  special  reflector,  called  a  "  vertical  illuminator/'  screwed 
into  the  microscope  tube  like  an  objective,  by  means  of  which 
light  is  directed  vertically  downward  on  the  polished  surface,  and 
reflected  back  from  this  up  through  the  instrument  to  the  eye. 
Any  ordinary  microscope,  t>h&t  permits  sufficient  elevation  of 
the  tube  to  admit  the  vertical  illuminator  and  the  mounted 
specimen,  may  be  used  for  this  work.  If  the  petrographic  micro- 


FIG.  3.  — Prism 
Illuminator. 


FIG.  4.  —  Plane  Glass 
Illuminator. 


FIG.  5.  —  Short-mounted 
Objective. 


scope  is  used,  the  analyzer  ordinarily  should  be  thrown  out.  For  use 
with  daylight,  the  vertical  illuminator  is  a  totally  reflecting  prism 
(Fig.  3) ;  with  artificial  light,  more  even  illumination  is  secured 
by  the  use  of  a  reflector  consisting  of  a  plane  glass  disc  (Fig.  4). 

If  daylight  is  used,  care  must  be  taken  also  to  avoid  reflec- 
tions from  buildings,  trees,  or  clouds,  as  these  affect  the  colors 
of  minerals.  For  the  most  accurate  results,  an  open,  cloudless 
sky  is  necessary;  moreover  it  must  not  be  too  late  in  the  afternoon, 
as  the  quality  of  light  changes  rapidly  then,  and  becomes  somewhat 
polarized.  In  using  objectives  of  higher  power  than  about  16  mm. 
by  daylight,  the  short-mounted  form  (Fig.  5)  should  be  used,  as 
with  the  ordinary  mounting  only  a  narrow  strip  across  the  field  is 
properly  illuminated  by  the  prism. 

The  most  satisfactory  artificial  light  has  been  found  to  be  that 
of  an  electric  arc,  reduced  in  intensity  by  passing  through  a  ground 
glass  screen.  This  gives  practically  the  same  color  values  as 
daylight.  The  colors  of  minerals  have  been  standardized  by 
this  light  or  daylight. 

Methods  of  comparing  colors  under  the  microscope  will  be 
found  on  page  26.  All  bright  oblique  light  should  be  shut  off 
from  the  specimen  by  a  screen  which  allows  light  from  the  side 
to  fall  only  on  the  aperture  of  the  vertical  illuminator.  This 


WHITE/ 


OF  THE  OPAQUE  MINERALS  25 

will  eliminate  the  confusion  arising  from  the  mingled  effects  of 
vertical  and  oblique  light.  For  observing  transparent  minerals, 
the  screen  is  removed,  and  the  aperture  of  the  vertical  illuminator 
closed,  so  that  oblique  light  alone  falls  on  the  surface,  and  by  this 
means  their  color  by  transmitted  light  may  be  observed,  even  in 
very  small  grains. 

„  MAGNIFICATION 

The  most  convenient  magnification  for  ordinary  purposes  is 
about  50  diameters,  but  frequently  200  may  be  employed  to  ad- 
vantage. For  very  detailed  examination,  by  artificial  light,  this 
may  be  increased  to  800  or  more  (with  an  oil  immersion  objective). 
In  daylight,  400  diameters  is  about  the  upper  working  limit, 
as  above  this  the  image  is  usually  too  faint  and  blurred  to  be 
observed  accurately.  In  some  cases  a  low  power  objective,  or 
even  a  hand  lens,  may  be  used  advantageously  to  observe  the 
larger  relationships  of  minerals. 

PHOTOGRAPHING 

Microphotographs  of  polished  specimens  can  be  made  with 
little  difficulty.  They  are  very  useful  for  purposes  of  record  and 
comparison,  and  in  written  reports  give  a  clearer  idea  of  the 
material  than  could  possibly  be  conveyed  by  a  lengthy  description. 
Microphotography  may  be  accomplished  by  attaching  a  camera 
box  to  the  end  of  the  microscope,  which  itself  serves  as  the  camera 
lens.  Artificial  light  is  usually  employed  and  the  ground  glass 
screen  omitted,  to  permit  of  shorter  exposures.  In  general,  the 
equipment  and  procedure  are  the  same  as  in  metallography. 
The  colors  of  the  common  minerals  occurring  in  ores,  however, 
such  as  chalcopyrite,  bornite,  covellite,  etc.,  require  the  use  of 
color  screens  to  develop  contrast  between  two  or  more  minerals 
which  in  white  light  may  have  almost  the  same  photographic 
intensity.  For  instance,  with  an  ordinary  contrast  plate  and 
no  color  screen,  in  the  combinations  bornite  and  chalcocite, 
covellite  and  chalcocite,  and  chalcopyrite  and  galena,  the  compo- 
nent minerals  have  practically  the  same  color  values,  and  often 
the  contact  between  them  is  hardly  visible.  But  with  a  mono- 
chromatic screen  which  will  make  one  of  each  pair  appear  dark, 
beautiful  results  may  be  obtained. 

For  color  screens,  Wratten  and  Wainwright  light  filters  have 
been  used  with  great  success  in  this  sort  of  microphotography,  and 


26  MICROSCOPICAL  DETERMINATION 

the  following  grades  have  been  employed:  K2  =  yellow;  A  =  red; 
B  =  green;  C  =  blue.  The  red  of  course  can  be  used  success- 
fully only  with  panchromatic  plates.  The  others  can  be  used  with 
Cramer  Contrast  or  Seed  L  ortho,  non-halation  plates. 

The  following  data  will  serve  as  a  guide  in  photographing  these 
or  similar  combinations  of  minerals. 

WHITE  LIGHT.  —  Cramer  Contrast  plate  —  sphalerite  and  galena ; 
etched  chalcocite;  pyrite,  galena,  or  chalcopyrite,  in  gangue. 

YELLOW  SCREEN.  —  Cramer  Contrast  plate  —  bornite  and  chal- 
cocite; bornite  and  chalcopyrite;  covellite  and  chalcocite;  covellite 
and  chalcopyrite;  pyrite  and  chalcopyrite;  "  mottled  chalcocite." 

GREEN  SCREEN.  —  Cramer  Contrast  or  Seed  L  Ortho  (n.h.)  plate 
-  same  as  with  yellow  screen,   but   Cramer   Contrast  requires 
very  long  exposure,  and  Seed  plate  does  not  give  so  bright  a 
negative.     The  yellow  screen  is  better  in  most  cases. 

BLUE  SCREEN.  —  Cramer  Contrast  or  Seed  L  Ortho  plate  - 
chalcopyrite  and  chalcocite;   tennantite  and  enargite. 

RED  SCREEN.  —  Panchromatic  plate  —  covellite  and  bornite. 

The  preceding  paragraphs  apply  best  to  pairs  of  minerals,  but 
when  three  or  more  are  to  be  photographed  the  best  combination 
to  use  is  Seed's  L  Ortho,  or  a  panchromatic  plate  *  with  the  K2, 
or  yellow  screen.  This  will  give  nearly  the  true  color  values  to  a 
complex  combination  of  minerals,  such  as  sphalerite,  galena,  chal- 
copyrite, tennantite  or  tetrahedrite,  bornite,  and  gangue,  a  not 
unusual  assemblage  in  certain  types  of  sulphide  ore. 

The  table  of  exposures  given  on  the  following  page  is  not  com- 
plete, but  covers  the  parts  likely  to  be  of  use  in  ore  photography, 
both  as  regards  magnifications  and  combinations  of  minerals. 

COLOR  COMPARISON 

The  accurate  determination  of  the  colors  of  minerals  is  one 
of  the  most  important  steps  in  their  identification,  and  for  this 
reason  demands  careful  attention.  It  is  also  one  of  the  most 
difficult  things  to  accomplish,  and  for  the  most  precise  distinctions 
requires  a  certain  amount  of  practice.  The  importance  of  color 
is  due  to  the  fact  that  in  reflected  light  more  than  three-quarters 
of  the  sulphide  minerals  are  white,  or  nearly  white,  and  in  con- 

*  Very  recently  the  Eastman  Kodak  Co.  has  put  on  the  market  the  Wratten  M  Plate, 
especially  designed  for  microscopic  photography.  It  is  highly  efficient,  and  their  accom- 
panying booklet,  "  Photomicrography,"  is  also  highly  to  be  recommended  to  workers  in 
this  line. 


HI 


OLOR 


OF  THE  OPAQUE  MINERALS 


EXPOSURES 


27 


Screen 

None 

Green  "B" 

Yellow  "K2" 

Blue  "  C  " 

Red 
"A" 

Plate 

C.C. 

SLO 

C.C. 

w+w 

SLO 

C.C. 

W+W 

SLO 

C.C. 

W+W' 

W+W 

Magnification: 
45 
55 
65 
85 
130 
170 
250 
300 
375 
750 
840  ± 
1670± 

1 

2 

"l'* 

'."Si' 

60' 
1*15 

> 

2 
2^ 
3 
4 
5 
7 

10  ' 
15 

"Y 

.... 

'ii' 

"2 

2 

'2 

"4" 

3 
6 

2* 

5- 
5+ 
10 

3* 

12+ 
20 

| 

10 
12 
15 

Key:  —        SLO  =  Seed  L  Ortho,  non-halation  plate. 

C.  C.  =  Cramer  Contrast  plate. 

W  +  W  =  Wratten  and  Wainwright  Panchromatic  plate. 
*  =  minutes.     Ordinary  figures  indicate  seconds. 

Note.  —  These  exposures  are  figured  for  the  B.  &  L.  Model  D  Balopticon,  but  the 
same  proportions  will  hold  for  light  of  different  intensity. 

sequence  comparatively  delicate  distinctions  must  be  made  to 
separate  this  large  class  into  smaller  groups  which  may  be  more 
readily  sub-divided  by  microchemical  tests.  Fortunately  many 
of  these  minerals  possess  various  tints,  such  as  creamy,  or  bluish, 
or  grayish  white,  and  may  conveniently  be  separated  into  groups,  by 
comparison  with  a  standard.  The  primary  standard  is  pure  galena, 
and  the  position  in  the  color  scale  of  every  white  mineral  is  estab- 
lished by  its  appearance  when  compared  with  galena.  There  are 
also  subordinate  standards  for  the  different  qualities  of  white,  such 
as  silver  (pure,  not  coin  silver)  for  the  creamy  white  minerals, 
tetrahedrite  for  the  grayish  white,  and  cuprite  for  the  bluish  white. 
For  distinctly  gray  minerals,  dark  colored  sphalerite  may  be  used, 
if  necessary. 

The  comparison  may  be  made  in  several  ways.  The  essential 
principle  is  to  get  the  two  objects  to  be  compared  as  close  together 
as  possible  in  the  field  of  vision.  The  following  method  has  been 
used  in  this  work  and  found  to  be  very  satisfactory.  Each  of  the 
color  standards  is  so  ground  that  one  side  of  the  polished  surface 
is  bounded  by  a  straight  line;-  the  specimen  to  be  compared  is 
similarly  prepared  and  is  mounted,  together  with  the  standard, 
so  that  the  straight  edges  of  the  two  are  in  contact  and  the  two 


28 


MICROSCOPICAL  DETERMINATION 


polished  surfaces  are  in  the  same  plane,  and  can  be  directly  com- 
pared under  the  microscope.  (See  Fig.  6.)  Exceedingly  delicate 
comparisons  of  color  may  be  made  in  this  way,  and  usually  it  is 
easy  to  prepare  the  specimen,  though  in  the  case  of  small  grains  in- 
cluded in  other  minerals  the  specimen  has  to  be  cut  down  care- 


standard 


Metal  plate 
New  mineral  Standard  mineral   / 


Mounting 


Metal  plate 


SIDE  VIEW 


Mounting: 


TOP  VIEW 


FIG.  6.  —  Method  of  Comparing  Colors. 

fully  until  an  area  of  the  mineral  in  question  is  at  the  straight  edge. 
Another  method  employs  a  comparison  eyepiece,  which  projects 
the  images  from  two  separate  objects  into  one  eyepiece,  so  that  one- 
half  the  field  is  occupied  by  the  image  of  one  object  and  the  other 
half  by  that  of  the  other.  This  has  the  advantage  that  a  small 
area  in  the  middle  of  a  specimen  may  be  easily  and  quickly  com- 
pared with  the  standard. 

The  beginner  in  this  work  may  at  the  very  outset  experience 
some  difficulty  in  this  matter  of  color  determination,  but  it  has  been 
found  that  the  ability  to  distinguish  minute  differences  in  color 
grows  very  rapidly  with  experience,  and  it  is  astonishing  how  much 
more  can  be  seen  after  a  week's  work  than  at  the  start. 

As  stated  above,  these  determinations  are  comparative,  with 
an  arbitrary  standard,  because  the  eye  is  not  accurate  enough  to 
carry  such  slight  differences.  Moreover,  except  in  the  case  of 
the  distinctly  colored  minerals,  the  differences  are  so  slight  that 
even  spectroscopic  measurements  of  the  reflected  wave  length 
would  probably  be  ineffective.  The  books  on  colors  and  color 
standards  deal  with  far  brighter  colors  than  most  of  the  tinted 
white  minerals  show.  Ridgway's  book  on  "  Color  Standards  and 
Nomenclature/'34  giving  1100  named  colors,  is  the  best  and  latest 
of  its  sort.  He  gives  colored  plates  reproducing  the  shades  and 
tints  of  the  spectrum  colors,  with  a  white  blank  for  comparison 
with  the  lightest  tint  of  each  color.  Unfortunately,  except  for 
the  distinctly  colored  and  gray  minerals,  which  are  relatively 
few  in  number,  all  the  sulphide  minerals  have  colors  falling  some- 
where between  pure  white  and  his  lightest  tint,  usually  much 


£/       COLOR 


OF  THE  OPAQUE   MINERALS  29 

nearer  the  white  end,  so  his  standards  are  of  little  use  in  this 
connection. 

HARDNESS  DETERMINATION 

Hardness  is  often  indicated  by  the  character  of  the  polish  which 
a  mineral  will  take.  Very  tiafd  minerals  may  be  either  shiny 
and  very  much  pitted,  like  magnetite,  or  dull  and  scratched,  like 
pyrite.  Medium  minerals  are  smooth,  or  somewhat  pitted,  ac- 
cording to  their  brittleness.  These  can  usually  be  smoothed  off 
rather  easily.  Enargite  is  often  considerably  pitted,  especially 
with  insufficient  polishing.  Soft  minerals  practically  always 
have  a  smooth,  unpitted  surface,  but  they  are  usually  very  easily 
scratched.  An  exception  is  galena,  which  usually  shows  triangular 
pits,  not  removed  by  later  polishing,  where  fragments  have  been 
torn  out  along  the  cubic  cleavage  by  the  coarse  grinding.  Or- 
dinarily even  minerals  with  perfect  cleavage  give  no  indication 
of  this  on  the  polished  surface. 


c 


edle^- 


Handle  j  Needle 

FIG.  7.  —  Needle  Mounted  for  Testing  Hardness. 

For  determining  the  hardness  of  opaque  minerals  on  the  pol- 
ished surface,  it  is  convenient  to  use  a  fine  needle  (No.  10  Sharp), 
mounted  at  an  angle  of  about  30°  to  a  J-ounce  handle,  5  inches 
long.  (See  Fig.  7.)  The  idea  is  to  have  weight  enough  in  the 
handle,  when  held  near  the  middle,  to  cause  the  needle  point  to 
scratch  soft  minerals  without  additional  pressure  of  the  hand.  This 
may  be  handled  directly  under  the  microscope,  so  that  very  small 
areas  may  be  tested  easily. 

Careful  investigation  with  specially  designed  apparatus  per- 
mitting accurate  determination  of  the  hardness  of  minerals  on  the 
polished  section  indicates  that  many  minerals  possess  distinctly  dif- 
ferent hardness  in  different  crystal  directions,  so  that  two  random 
sections  of  the  same  mineral  in  a  polished  section  might  give  discord- 
ant results  on  accurate  measurement,  and  lead  to  the  erroneous 
supposition  that  two  different  minerals  were  present.  On  this  ac- 
count, it  has  not  been  considered  advisable  in  this  work  to  carry  this 
determination  of  hardness  too  far,  lest  confusion  arise  from  the  over- 
lapping of  hardness  ranges  of  various  minerals.  Accordingly,  only 
three  degrees  of  hardness  are  recognized:  high,  medium  and  low. 


30  MICROSCOPICAL  DETERMINATION 

With  oblique  light,  harder  minerals  in  contact  with  softer  ones 
show  a  bright  rim  on  the  side  of  the  harder  mineral  towards  the 
direction  of  illumination  (reversed,  of  course,  in  the  field  of  view 
of  the  microscope).  With  the  prism  illuminator  this  effect  is  most 
delicately  observed  when  the  area  under  observation  is  close  to  the 
edge  of  the  field  of  view  nearest  the  observer.  This  is  the  best 
method  of  determining  the  relative  hardness  of  minerals. 

MICROCHEMICAL  TESTS 

Microchemical  tests  are  the  most  important  of  the  means  of 
classification,  and  in  most  cases  are  absolutely  necessary,  owing  to 
the  fact  that  very  many  minerals  have  practically  the  same  phys- 
ical characteristics. 


(PI 


FIG.  8.  — Pipette. 

Method  of  Application.  —  The  desired  chemical  reagent  is  best 
applied  by  means  of  a  capillary  pipette,  so  that  a  very  small  drop 
may  be  placed  on  the  polished  surface.  This  drop  should  be  be- 
tween 0.25  mm.  and  2  or  3  mm.,  though  in  some  cases  it  is  allow- 
able to  use  a  larger  drop,  if  the  area  of  the  mineral  to  be  tested  is 
considerable.  The  pipette  may  be  made  of  small  soft  glass  tubing 
drawn  out  to  a  fine  point,  so  that  the  opening  is  about  0.25  mm. 
in  diameter.  It  is  convenient  to  have  the  tip  of  the  pipette  bev- 
elled, to  facilitate  the  flow  of  reagent  when  the  instrument  is 
touched  in  an  inclined  position  to  the  specimen.  (See  Fig.  8.)  The 
surface  to  be  tested  must  be  made  absolutely  clean  by  first  rubbing 
on  the  rouge  block,  as  any  dirt  or  grease  may  not  only  render  diffi- 
cult the  deposition  of  a  drop  of  the  reagent  on  the  surface,  but  also 
may  retard  or  prevent  reaction  which  would  otherwise  take  place, 
and  so  nullify  the  test.  A  separate  pipette  should  be  provided 
for  each  reagent  and  labelled  appropriately.  After  using,  the 
pipette  should  invariably  be  freed  of  excess  reagent,  either  by 
washing  or  otherwise;  failure  to  observe  this  precaution  may  lead 
to  annoyance  and  even  to  erroneous  results. 

The  application  of  the  reagent  may  generally  be  best  performed 
directly  in  the  field  of  view  of  the  microscope,  so  that  any  point 
may  be  selected  and  treated,  thus  permitting  the  testing  of  very 
small  grains  of  a  mineral  surrounded  by  other  opaque  minerals  or 
by  gangue.  (See  Fig.  9.)  This  is  important,  as  hybrid  reactions 
are  often  obtained  by  etching  mixtures  of  minerals,  leading  to 


HI 


OLOR 


OF  THE  OPAQUE   MINERALS 


31 


confusion  in  identification.  This  method  of  application  of  the 
reagent  has  the  advantage  that  the  very  beginning  of  a  reaction 
may  be  observed,  and.  the  result  followed  through  to  the  end. 
This  is  very  essential  for  some  reactions,  which  start  almost  in- 
stantly, and  would  be  too  far  advanced  to 
observe  if  the  specimen  had*  to  be  taken 
from  under  the  microscope,  fne  reagent 
applied,  and  the  specimen  replaced  for  in- 
spection of  the  effect.  Moreover,  instead  of 
spoiling  the  whole  specimen,  only  so  much 
of  the  surface  is  etched  as  is  desired,  so 
that  comparison,  may  be  made  immediately 
of  etched  and  unetched  areas  of  a  mineral. 
Reactions.  —  After  the  reagent  is  applied, 
a  reaction  is  watched  for.  If  there  is  no 
indication  that  any  change  is  beginning, 
either  in  the  mineral  or  reagent  (except  pos- 
sibly that  the  latter  evaporates  rapidly),  in 
about  twenty  seconds,  the  reaction  is  pro- 
nounced negative.  If  there  is  a  reaction, 
its  rate,  and  the  changes  both  in  reagent 
(coloration,  evolution  of  gas,  etc.)  and 
mineral,  must  be  carefully  noted.  Then  FlG-  9.  — Method  of  Using  Pi- 

..!  . .        .1  .  .1  pette  (hardness  may  be  tested 

without  unmounting  the  specimen,  the  re-  fn  thev  same  way/usmg  t,he 
agent  is  gently  rinsed  off  with  water  or  al-  mounted  needle. — See  Fig.  7). 
cohol,  and  before  rubbing,  which  would  destroy  any  coating  that 
had  been  formed,  the  specimen  is  examined  again  to  observe  the 
nature  of  the  change,  whether  tarnish,  or  coating  (black  by  vertical, 
and  white  or  colored  by  oblique,  light),  or  solution  of  the  surface, 
shown  by  a  roughening,  with  or  without  blackening.  Sometimes 
etch-figures  are  developed.  Some  minerals  are  tarnished  by  acid 
fumes,  while  the  acid  itself  leaves  them  apparently  unchanged; 
this  results  in  a  halo  of  alteration  surrounding  the  drop  of  reagent, 
but  no  evident  attack  on  the  area  actually  covered  by  the  drop. 

Then  the  specimen  is  dried  off,  rubbed  on  the  rouge  block  and 
again  examined,  to  determine  whether  the  tarnish  or  coloration 
of  the  mineral  is  persistent,  or  whether  it  rubs  off,  leaving  a  clean 
surface  with  practically  the  original  color  of  the  mineral. 

The  different  types  and  speeds  of  reaction  are  often  very  im- 
portant in  distinguishing  minerals,  several  of  which  might  be  at- 


32  MICROSCOPICAL  DETERMINATION 

tacked  by  the  same  reagent,  but  in  different  ways.  It  is  therefore 
necessary  to  note  carefully  each  feature  of  the  reaction. 

Some  reactions  are  affected  by  the  presence  of  other  minerals.  In 
testing  very  small  areas,  the  drop  of  reagent  necessarily  overlaps 
onto  the  surrounding  minerals,  some  of  which  may  be  affected. 
Calcite  is  particularly  apt  to  obscure  reactions  with  acid  by  neu- 
tralizing the  reagent  so  quickly  that  it  does  not  have  time  to  make 
appreciable  attack  on  the  mineral  for  which  it  was  intended.  This 
possibility  of  interference  of  other  minerals  is  the  one  perhaps  most 
likely  to  cause  erroneous  results,  but  with  the  exercise  of  care  in 
suspicious  cases,  difficulties  may  usually  be  avoided.  In  case  of 
doubt,  it  is  best,  wherever  possible,  to  find  a  grain  of  the  mineral 
in  question  large  enough  entirely  to  hold  a  small  drop  of  the 
reagent. 

Reagents.  —  The  following  reagents  have  been  used,  to  greater  or 
less  extent :  the  first  eight  have  been  found  most  useful.  With 
further  work,  undoubtedly  other  reagents  will  be  found  to  prove 
valuable  in  special  cases.  The  symbols  or  abbreviations  in  the 
list  below  are  the  same  as  those  used  in  the  determinative  tables 
of  this  book. 

LIST  OF  REAGENTS 

1.  HN03  —  Concentrated  nitric  acid  diluted  with  equal  volume  of  water. 

2.  HN03  cone.  —  Concentrated  nitric  acid.     70%  (sp.  gr.  1.42). 

3.  KCN  —  20%  solution. 

4.  HC1  —  Concentrated  hydrochloric  acid  diluted  with  equal  volume  of  water. 

5.  HC1  cone.  —  Concentrated  hydrochloric  acid.     37%  (sp.  gr.  1.19). 

6.  Aq.  Reg.  —  Freshly  made  Aqua  Regia  (3  HC1  +  HN03). 

7.  FeCl3  —  20%  solution. 

8.  KOH  —  Concentrated  solution. 

9.  NaOH  —  Concentrated  solution. 

10.  NH4OH  —  28%  solution. 

11.  (NH^S*. 

12.  Iodine  —  Solution  in  alcohol. 

13.  KsFe(CN)6  —  20%  solution. 

14.  K4Fe(CN)6  —  20%  solution. 

15.  H2S04  —  dilute  or  concentrated. 

16.  AgN03  —  3%  —  10%  solution. 

17.  KClOs  —  Saturated  solution,  followed  by  cone.  H2S04. 

The  reagents  are  used  cold,  unless  otherwise  stated.  Hot 
reagents  are  desirable  in  certain  cases,  though  they  usually  have 
to  be  applied  to  the  whole  surface,  thus  making  it  necessary  to 
re-polish  the  specimen  for  further  examination.  - 


WHITE/       COLOR 


MINERAL  COMPOSITION  AND  IDENTITY 

» 

THE  microscopic  examinatioiUiOf  polished  surfaces  is  competent 
to  detect  mechanical  mixtures  of  minerals,  even  when  exceedingly 
minute.  Moreover,  it  may  be  relied  on  to  perceive  even  very 
slight  color  differences,  due  not  to  mechanical  mixture,  but  to 
variation  in  chemical  composition.  Finally,  specimens,  which 
have  been  shown  by  crystallographic  or  other  means  to  belong 
to  the  same  species  and  which  appear  physically  similar  under  the 
microscope,  may  show  differences  in  microchemical  behavior 
which  must  signify  that  the  mineral  in  question  is  actually  variable 
in  chemical  composition.  It  must  be  borne  in  mind,  however, 
that  color  differences  may  also  be  caused  by  difference  in  perfec- 
tion of  polish;  the  variations  due  to  actual  differences  in  composi- 
tion, however,  are  ordinarily  exceedingly  slight,  while  those  due  to 
imperfection  of  surface  may  be  avoided  by  taking  sufficient  care  in 
polishing,  but  with  growing  experience  due  allowance  can  be  made 
for  the  effect  produced  on  the  true  color  by  minute  pits  and 
scratches. 

For  purposes  of  discussion  of  composition  and  identity,  miner- 
als may  conveniently  be  divided  into  a  number  of  groups  according 
to  the  prevailing  view. 

1.  Minerals  of  thoroughly  established  identity  and  constant 
composition,  such  as  pyrite  or  chalcopyrite. 

2.  Minerals  of  definitely  established  identity  and  variable  com- 
position, such  as  tetrahedrite  or  polybasite. 

3.  Minerals  of  fairly  well  established  identity,  supposed  to  be 
constant  in  composition,  such  as  mohawkite. 

4.  Minerals  described  as  definite  species  though  believed  by 
some  to  be  mixtures,  like  cubanite. 

With  regard  to  these  groups,  mineralographic  examination  leads 
to  the  following  conclusions. 

1.  The  validity  of  this  group  is  clearly  established. 

2.  Some  members  of  this  group  have  been  shown  to  owe  their 
variable  composition  to  the  presence  of  other  elements  in  chemical 
combination  with  the  normal  constituents  of  the  mineral.     This 

33 


34  MICROSCOPICAL  DETERMINATION 

variation  in  some  cases  does  not  appear  to  affect  the  physical  or 
microchemical  properties.  Here,  for  example,  belongs  pyrrhotite, 
which  has  a  variable  amount  of  sulphur  in  excess  of  FeS,  but 
which  does  not  show  any  perceptible  variation  in  properties  and 
appearance  under  the  microscope.  Thus  it  appears  that  in  the 
case  of  solid  solutions,  such  as  pyrrhotite  has  been  shown  to  be,  the 
variation  may  not  appear  in  any  way  other  than  by  a  chemical 
analysis.  In  other  cases  there  are  small  but  perceptible  differences, 
as  in  the  case  of  polybasite,  which  shows  by  analysis  a  rather 
wide  variation  in  composition,  as  regards  the  ratio  of  bases 
present. 

The  analyses  of  the  tetrahedrite-tennantite  series  (Cu8Sb2S7- 
Cu8As2S7)  are  so  variable  that  Hintze  and  Dana  give  different 
formula,  and  even  then  have  to  assume  that  various  metals 
replace  the  copper  to  a  greater  or  less  extent.  As  a  matter  of 
fact,  microscopic  examination  of  many  specimens  shows  that 
these  minerals,  even  in  good  crystals,  have  a  strong  tendency  to 
be  intergrown  with  other  sulphides,  thus  giving,  in  most  of  these 
instances,  a  simple  explanation  of  the  variation  in  composition 
shown  by  the  analyses,  and  also  accounting  for  many  of  the  extra 
metals  present.  Pure  material  of  this  series  shows  but  slight 
variation  in  color,  the  pure  arsenic  and  pure  antimony  compounds 
being  slightly  though  distinctly  different,  while  the  intermediate 
members  of  the  series  frequently  cannot,  without  very  close 
scrutiny,  be  distinguished  from  either  end  member.  The  copper 
may  be  in  part  replaced  by  silver,  without  change  in  color,  though 
the  microchemical  properties  are  affected.  It  is  quite  probable 
that  other  metals  may  occur  similarly,  without  changing  the  phys- 
ical properties  of  the  mineral. 

Steinmannite,  which  is  galena  with  chemically  combined  arsenic 
and  antimony,  exactly  resembles  galena  in  physical  properties, 
but  is  somewhat  different  in  microchemical  behavior. 

Many  analyses  of  galena  show  the  presence  of  other  elements, 
such  as  arsenic,  antimony,  silver  and  sometimes  bismuth,  which 
the  microscope  has  shown  to  be  chemically  combined  with  it, 
and  which  change  only  the  microchemical  properties.  Some  so- 
called  argentiferous  galenas  are  found  on  microscopic  examination 
to  contain  small  amounts  of  distinct  silver  minerals,  which  account 
for  the  silver  content  in  these  cases. 

The  various  cobalt  and  nickel  arsenides  (such  as  smaltite,  skut- 


OLOR 


OF  THE  OPAQUE   MINERALS  35 

terudite,  chloanthite,  etc.)  occur  in  mixtures  with  all  proportions 
of  these  various  minerals,  along  with  minerals  not  belonging  to 
the  series.  The  crystals  appear  to  be  zoned,  and  this  structure  is 
generally  revealed  by  etching,  if  not  visible  before.  It  is  also  sug- 
gested by  differences  in  solubilities  that  have  been  noted  in  pre- 
vious chemical  work  on  these  hiinerals.  Inclusions  of  minerals  not 
of  the  series  have  a  strong  tendency  to  take  the  form  of  suspended 
droplets  or  blebs  in  the  host,  like  an  emulsion.  It  is  accordingly 
not  surprising  that  analyses,  even  of  crystals,  have  given  variable 
results,  and  consequently  some  of  the  formulae  assigned  to  these 
minerals  are  probably  wrong. 

Other  members  of  the  second  group  owe  their  supposed  variation 
to  mechanical  admixture,  such  as  bornite.  Analyses  of  bornite  have 
varied  between  wide  limits,  and  though  it  has  long  been  recognized 
that  this  variation  is  usually  due  to  mechanically  admixed  chal- 
cocite,  it  has  been  a  great  question  whether  bornite  really  is  of 
constant  composition  or  not.  In  1905,  Harrington18  analyzed  pure 
material  from  several  localities,  both  massive  and  in  crystals, 
and  established  the  definite  formula  CusFeS^  which  has  since 
been  generally  accepted.  Mineralographic  study  has  shown  that 
very  rarely  indeed  is  absolutely  pure  bornite  found  in  amounts 
large  enough  to  analyze,  and  that  the  usual  impurity  is  chalcocite, 
either  intergrown  with  it,  or  formed  in  it  as  the  result  of  altera- 
tion, though  chalcopyrite  is  not  uncommon,  and  other  sulphides 
also  occur.  A  large  area  of  especially  pure  massive  bornite, 
subjected  to  a  careful  geometric  analysis  on  the  polished  surface, 
revealed  only  about  0.3  per  cent  of  impurity,  quite  uniformly  dis- 
tributed through  the  material  and  consisting  of  chalcocite,  chal- 
copyrite, tetrahedrite  and  galena.  Selected  portions  of  this 
material  were  sent  for  analysis  to  Dr.  E.  T.  Allen  of  the  Geo- 
physical Laboratory  in  Washington.  Dr.  Allen's  results1  agreed 
with  Harrington's  and  also  with  determinations  which  he  made  on 
some  of  Harrington's  material  and  on  other  specimens  of  pure 
bornite,  thus  positively  confirming  Harrington's  formula  for  the 
mineral.  Furthermore,  mineralographic  examination  of  polished 
surfaces  of  bornite  from  at  least  30  different  localities  has  revealed 
only  an  exceedingly  slight  variation  in  color,  and  practically  none 
in  microchemical  behavior. 

In  the  face  of  all  this  concordant  testimony  and  of  the  fact, 
noted  by  Harrington  and  confirmed  by  mineralographic  examina- 


36  MICROSCOPICAL  DETERMINATION 

tion  of  bornite  crystals  from  Butte,  Montana,  and  Cornwall, 
England,  that  many  crystals  of  this  mineral  are  pure  externally 
but  contain  much  intermixed  chalcocite  or  chalcopyrite  in  the 
interior,  the  conclusion  by  Kraus  and  Goldsberry23  that  bornite 
is  of  variable  composition  must  be  regarded  with  doubt,  especially 
as  it  appears  that,  although  they  sought  to  establish  the  purity 
of  their  material  by  microscopic  examination  with  reflected  light, 
they  unfortunately  failed  to  examine  the  material  actually 
analyzed.  Rogers36  has  come  to  the  conclusion  that  the  variability 
of  bornite  is  due  to  the  solid  solution  of  chalcocite  in  bornite,  and 
considers  that  Kraus  and  Goldsberry  have  proved  that  bornite 
really  is  variable  in  composition. 

This  occurrence  of  an  impure  basal  or  central  portion  in  crys- 
tallized material  is  found  to  be  surprisingly  common  in  most 
sulphides,  and  is  a  possible  source  of  error  which  should  be  guarded 
against  by  selecting  for  analytical  purposes  only  material  that  has 
been  very  carefully  and  thoroughly  examined  microscopically 
in  several  crystallographic  directions. 

3.  Minerals  of  this  group  have  been  shown  in  many  cases  to  be 
mechanical  mixtures :  mohawkite  or  schapbachite,  for  instance. 

4.  Some  minerals  of  this  group  have  been  definitely  shown  to  be 
mechanical  mixtures,  like  cubanite,  thus  confirming  the  prevalent 
opinion  about  them. 

Sphalerite  very  frequently  occurs  filled  with  an  "  emulsion  " 
of  minute  blebs  or  crystals  of  chalcopyrite,  often  arranged  along 
crystallographic  directions  in  the  sphalerite.  These  would  not 
appear  in  the  hand  specimen,  and  probably  would  not  be  visible 
even  in  thin  section,  especially  if,  as  is  apt  to  be  the  case,  the 
sphalerite  were  rich  in  iron,  and,  hence,  very  dark.  This  same 
"  emulsion  "  structure  occurs  in  much  greater  perfection  with 
bornite  in  chalcocite.  Here  there  are  often  beautiful  patterns 
of  bornite  droplets  in  the  chalcocite,  along  both  straight  and 
curved  lines.  The  droplets  are  often  elongated  in  one  direction, 
adding  to  the  variety  of  the  pattern,  and  approaching  the  typical 
"  eutectic  "  structure. 

OBSERVED   MIXTURES 

The  following  supposed  mineral  species,  some  of  which  have 
been  regarded  with  doubt  by  mineralogists,  have  been  shown 
with  more  or  less  certainty  by  mineralographic  study  to  be  mixtures 


OLOR 


OF  THE  OPAQUE   MINERALS  37 

of  two  or  more  minerals.  Some  of  these  constituents  are  known 
while  some,  mainly  because  of  their  minute  size,  are  as  yet  uniden- 
tified and  it  is  very  probable  that  several  of  them  are  actually 
new  species.  Unknown  constituents  have  been  treated  at  the 
appropriate  places  in  the  determinative  tables. 

Algodonite.  —  A  mixture,  or  yatergrowth  of  two  unknown  con- 
stituents, one  creamy,  the  other  grayish.  The  gray  is  rather  less 
in  amount,  on  the  average.  Determined  in  two  specimens. 

Alloclasite.  —  Probably  glaucodot,  or  a  similar  mineral,  with 
blebs  of  bismuth  (?)  and  a  bluish  gray,  soft  mineral,  scattered 
through  it.  There  is  also  native  gold,  but  this  was  recognized 
in  the  analyses.  Only  one  piece  was  polished,  but  the  material 
is  typical,  and  undoubtedly  the  finding  is  reliable.  The  specimen 
appears  like  an  emulsion  of  the  softer  minerals  in  the  glaucodot. 

Animikite.  —  Only  one  small  specimen  studied,  but  appears  to 
be  a  mixture  of  several  minerals.  Possibly  the  study  of  more 
material  would  establish  its  identity  more  fully. 

Barnhardtite.  —  A  mixture  resulting  from  the  alteration  of  chal- 
copyrite  to  covellite  and  chalcocite.  This  has  previously  been 
recognized  as  a  probable  mixture,  and  the  present  determination, 
made  on  a  piece  of  the  type  material,  confirms  this  conclusively. 

Brogniardite.  —  Appears  in  some  specimens  labelled  brogniardite 
to  be  a  mixture  of  ruby  silver,  galena  (?)  and  possibly  miargyrite; 
other  specimens  show  a  distinct  mineral  close  to  argentiferous 
jamesonite.  Very  dubious. 

Carrolite.  —  Probably  linnaBite  with  intergrown  bornite  and 
chalcopyrite.  Differs  only  slightly  from  linnseite  from  Siegen, 
agrees  with  linnseite  from  Mine  La  Motte,  Missouri,  and  is 
intimately  intergrown  with  enough  of  the  copper  minerals  to  fur- 
nish the  copper  required  by  the  formula  ascribed  to  carrolite. 
This  determination  is  not  final,  but  is  highly  probable. 

Chalcopyrrhotite.  —  Probably  a  mixture  of  chalcopyrite  with 
pyrrhotite,  and  some  chalmersite.  This  is  not  certain,  but  is 
highly  probable. 

Cubanite.  —  A  mixture  of  pyrite  or  pyrrhotite  with  chalcopyrite. 
Four  specimens,  from  different  localities,  were  examined  and  none 
was  homogeneous,  so  the  conclusion  that  cubanite  is  not  a  definite 
mineral  but  a  mixture  is  probably  reliable. 

Domeykite.  —  Three  specimens  have  the  same  characteristics  as 
algodonite.  Another  has  mixture  of  cream  and  purple. 


38  MICROSCOPICAL  DETERMINATION 

Harrisite.  —  A  pseudomorph  of  chalcocite  after  galena. 

Homichlin.  —  Chalcopyrite  altering  to  limonite,  with  a  little 
chalcocite.  This  was  determined  on  a  large  piece  from  the  type 
locality,  and  is  surely  reliable. 

Keweenawite.  —  A  mixture  of  smaltite,  niccolite,  and  domeykite, 
with  usually  a  little  stromeyerite  (?) .  Determined  from  two  pieces, 
one  identified  by  Kcenig  himself  as  keweenawite,  and  is  conclusive. 

Klaprotholite.  —  Alteration  product  of  an  unknown  creamy 
mineral  (?)  with  bismuth  (?)  and  covellite.  This  was  determined 
on  only  one  specimen  and  may  not  be  reliable,  though  as  the 
material  came  from  the  type  locality,  the  validity  of  klaprotholite 
seems  doubtful. 

Kobellite.  —  Intergrowth  of  galena  with  a  mineral  like  bismuth- 
inite  or  stibnite.  Also  determined  on  only  one  piece,  which  may 
not  have  been  representative. 

Mohawkite.  —  Mixture  of  two  unknown  constituents,  one 
creamy  and  one  grayish,  like  those  in  algodonite,  but  with  more 
of  the  gray,  and  the  two  (algodonite  and  mohawkite)  may  not 
be  exactly  the  same,  though  they  appear  very  similar. 

Plenargyrite.  —  Mixture  of  two  unknown  components,  one  soft 
and  bluish,  the  other  harder  and  creamier. 

Schapbachite.  —  Practically  the  same  as  plenargyrite,  but  with 
slightly  different  properties. 

Smaltite.  —  The  group  of  cobalt  and  nickel  arsenides  shows  prob- 
able zoning  of  different  members  in  any  one  crystal,  so  that  analyses 
cannot  be  relied  on  to  show  the  composition  of  individual  species. 

Tapalpaite.  —  A  mixture  of  creamy  and  grayish  unknown  com- 
ponents (?)  Perhaps  the  creamy  part  is  the  true  mineral.  One 
good  specimen  studied. 

Temiskamite.  —  A  mixture  of  maucherite  and  niccolite,  with  a 
little  cobaltite.  Determined  from  the  type  specimen,  and  surely 
reliable. 

PROBABLE  MIXTURES  AND  DOUBTFUL  MINERALS 

The  following  names  have  been  ascribed  to  certain  supposed 
mineral  species  which  are  regarded  in  the  standard  text-books 
as  doubtful.  None  of  these  has  been  examined  by  the  author, 
but  the  similarity  of  the  evidence  in  many  cases  to  that  for  sup- 
posed minerals  which  actually  have  been  examined,  tends  to 
indicate  that  examination  would  confirm  the  suspicion,  and  ac- 


WHITE/       COLOR 


OF  THE  OPAQUE   MINERALS 


39 


cordingly  they  are  tentatively  placed  under  this  heading,  pending 
investigation.  The  probable  nature  of  each  is  indicated  after 
the  name.  — >  indicates  "altering  to  "  or  "  altered  to."  For  mean- 
ing of  abbreviations  see  p.  46. 


Acanthite  =  Distorted  argentite" 
Alisonite  =  gn  — •>  cv  or  cc 
Antimon-luzonite  =  famatinite? 
Arite  =  NiSb  and  NiAs  (mixture) 
Arsenotellurite  -  Te,    As,    C?  ? 
Barracannite  —  impure  material 
Beyrichite  =  impure  polydymite 
Blueite  =  py 
Bolivianite  -  Ag,  Sb,  S? 
Bolivite  —  impure  material 
Bravoite  —  impure  material 
Cantohite  =  bn  — »  cv 
Castillite  =  bn  and  Ag? 
Clarite  =  en 
Clayite  -  Pb,    Cu,    Sb,    As,    S 

(altn.  prod.?) 

Coolgardite  —  impure  material 
Corynite  -  Ni,  (Sb  As),  S 
Crucite  =  arsenopyrite  — >  hem- 
atite 

Cuproplumbite  =  gn  — >  cc  and  cv 
Daleminzite  =  Ag2S  (orth.) 
Danaite  =  Cobaltif .   arsenopyrite 
Dimorphite  —  As4S3? 
Ducktownite  —  impure  material 
Durfeldtite  -  (Ag,  Pb,  Sb,  S)? 
Fieldite  =  impure  td. 
Folgerite  =  pentlandite 
Grunauite=  impure  polydymite? 
Guadalacazarite  =  Hgs  and  ZnS? 
Gunnarite  =  pentlandite 
Heazlewoodite  =  pentlandite 
Histrixite  —  Cu5Fe5Bii4Sb4S37  (mix- 
ture)? 

Horbachite  -4  Fe2S3  •  Ni2S3  (mix- 
ture) . 


Huascolite  =  gn  and  si? 

Jaipurite  —  CoS? 

Joseite  =  tetradymite? 

Kaneite  =  Mn,  As  ?  ? 

Kilbrickenite  =  geocronite 

Kroeberite  —  (not  analyzed) 

Lautite  =  en  and  As 

Ledouxite  —  impure  material 

Leviglianite  —  Ag2S  orth.  and  Fe? 

Marrite  —  (not  analyzed) 

Metastibnite  —  St^Ss  (amor- 
phous)? 

Miillerine  =  impure    krennerite 

Nepaulite  =  td 

Orileyite  =  impure    domeykite? 

Osbornite  -  Ca,  Ti?,  S,  O  (me- 
teoric) 

Pacite  =  impure  arsenopyrite? 

Plumbomanganite  —  (MnPb),  S? 

Plumbostannite-Pb,  Sn,  Sb,  S? 

Quirogite  =  impure  galena 

Silaonite  —  impure  material 

Silverphyllinglanz  =  nagyagite?. 

Sommarugaite  =  Aurif.  gers- 
dorffite 

Tombazite  =  py 

Valeriite  -  Cu,  Fe,  Al,  Mn2,  H2, 
O,  S?? 

Warrenite  =  jamesonite  and 
zinkenite 

Wehrlite  -  Bi,  Te,  S,  Ag? 

Whartonite  =  pyrite 

Wolfachite  —  near  corynite 

Youngite  -  Pb,  Zn,  Fe,  S,  Mn? 

Zorgite  =  clausthalite  +  uman- 
gite? 


PLAN  OF  CLASSIFICATION 

THE  plan  of  classification  in  the  tables  that  follow  is  based 
first  of  all  on  the  color  of  polished  minerals  as  seen  under  the 
microscope.  The  next  test  is  relief  or  hardness.  Subordinate  to 
relief  in  part  of  the  tables,  color  is  again  employed  as  a  basis  for 
subdivision.  Microchemical  tests  come  last. 

COLOR 

The  opaque  minerals  are  here  divided  into  three  main  groups 
primarily  by  determination  of  color  —  that  is,  the  color  of  the  min- 
eral as  observed  alone  under  the  microscope,  not  compared  with 
anything  else.  If  the  mineral  has  a  decided  color,  it  is  called 
colored.  If  very  pale  colored,  or  white,  it  is  classified  as  white. 
If  distinctly  gray,  it  is  put  under  that  heading. 

Colored.  —  If  a  mineral  has  a  distinct  color,  its  identification 
is  very  simple,  as  there  are  comparatively  few  colored  opaque 
minerals.  Chalcopyrite,  for  instance,  is  yellow,  covellite  is  blue,  etc. 

White.  —  If  the  mineral  is  white,  or  approximately  so,  the  identi- 
fication on  the  polished  surface  is  more  complicated,  because  a 
large  majority  of  the  sulphides  fall  in  this  class.  It  is,  therefore, 
necessary  to  establish  three  subdivisions  on  the  basis  of  hardness 
or  relief.  The  subdivision  with  high  relief  needs  no  further  color 
determination,  except  incidentally,  but  the  other  two,  medium 
and  low  relief,  are  so  extensive  as  to  require  still  further  subdivi- 
sions by  color.  This  is  made  by  color  comparison  with  a  standard, 
as  described  on  page  26.  It  is  exceedingly  important  that  this 
step  be  made  with  care,  because  of  the  close  similarity  in  appear- 
ance of  many  minerals.  In  fact,  this  is  one  of  the  most  important 
and  effective  points  in  the  classification,  and  without  it  the  task 
of  identifying  a  mineral  in  either  of  these  groups  would  be  tedious 
and  difficult.  With  practice,  the  differences  between  the  color 
subdivisions  are  easily  recognized,  the  eye  rapidly  acquiring 
facility  in  detecting  variations.  To  aid  identification,  in  the  case 
of  minerals  whose  tints  fall  between  two  of  the  established  groups, 
the  mineral  description  in  full  is  put  in  the  group  it  appears  to 
approach  most  closely  and  a  reference  to  this  is  given  in  the  ap- 
propriate place  in  the  other  group.  Unfortunately,  there  are 

40 


WHITE/       COLOR 

^^^^^•IM^MMi^^^^^  ^v»^  -^ 


OF  THE  OPAQUE  MINERALS  41 

a  number  of  such  minerals,  but  it  is  believed  that  with  the  full 
cross-referencing  no  trouble  will  arise  from  this  source. 

The  secondary  subdivisions  by  color,  established  by  this  com- 
parison, are  as  follows: 

Galena  White.  —  This  term  has  been  used  to  denote  the  color  of 
galena  itself,  and  in  this  group  are  placed,  in  one  subdivision,  all 
minerals  that  appear  pure  whitfe  against  galena,  and  in  the  other, 
all  those  the  same  color  as  galena,  or  only  very  slightly  different. 

Creamy  White.  —  This  is  approximately  the  color  of  pure  silver 
compared  with  galena,  and  in  this  group  are  placed  all  minerals 
appearing  creamy  white  against  galena.  A  division  has  been  made 
of  this  group,  using  silver  as  a  standard,  into  minerals  paler  than 
silver,  or  the  same  color,  and  minerals  darker  than  silver. 

Bluish  White.  —  Minerals  appearing  bluish  white  against  galena. 
Many  of  these  are  transparent. 

Pinkish  White. — Minerals  appearing  pinkish  white  against  galena. 

Grayish  White.  —  Minerals  appearing  grayish  white  or  grayish- 
greenish  white  against  galena. 

Other  color  values  within  the  limits  of  white  exist,  but  they  are 
too  indefinite  for  separate  grouping  and  are  noted  by  a  qualifying 
adjective  in  the  description  of  the  mineral's  color. 

Gray.  —  If  a  mineral  is  distinctly  gray,  it  may  be  compared 
with  dark  sphalerite,  though  this  is  not  usually  necessary,  and  may 
be  used  as  a  supplementary  test.  Some  hard  white  minerals 
polish  with  difficulty,  and  often  appear  gray,  because  finely  pitted. 

Transparent  and  gangue  minerals.  —  Some  sulphides  are  trans- 
parent. This  property  may  be  detected  by  observing  with  oblique 
light,  which  may  be  obtained  by  temporarily  stopping  the  aper- 
ture of  the  vertical  illuminator.  Transparent  red  minerals,  like 
cuprite  or  ruby  silver,  reflect  the  complement  of  their  transmitted 
color  and  appear  bluish.  All  the  transparent  sulphides  have  a 
very  high  index  of  refraction,  and  probably  for  this  reason  appear 
bright  on  the  polished  surface  by  vertically  reflected  light.  Sphal- 
erite is  the  darkest  of  these  and  appears  grayer  than  any  other 
sulphide.  Most  gangue  minerals  are  transparent,  and  practically 
all  appear  decidedly  darker  than  sphalerite,  which  thus  occupies 
an  intermediate  position.  The  transparent  gangue  minerals, 
usually  with  a  fairly  low  index  of  refraction,  appear  dark  gray 
because  the  light  in  large  part  penetrates  the  grain  and  is  dispersed 
and  lost  on  the  irregular  lower  surface,  while  only  a  small  portion 
is  reflected  back  from  the  polished  face. 


42  MICROSCOPICAL  DETERMINATION 

Effect  of  surface  on  color.  —  Poorly  polished  surfaces  appear 
darker  than  smooth  ones,  and  pits  on  the  polished  surface  appear 
black,  because  most  of  the  light  is  scattered  from  the  uneven 
bottom  and  sides.  Minerals  with  high  relief,  surrounded  by  much 
softer  ones,  appear  to  be  surrounded  by  a  black  rim,  due  to  the 
sloping  contact  between  the  higher  and  lower  mineral,  which 
deflects  the  light  obliquely.. 

HARDNESS 

The  second  main  division  is  based  on  hardness,  as  determined 
either  by  the  actual  relief  of  a  mineral  on  the  polished  surface 
against  a  known  constituent,  by  the  character  of  the  polish  ob- 
tained, or  by  scratching  directly  under  the  microscope,  with  a 
fine  needle  point.  By  this  means,  three  main  groups  are  estab- 
lished, which  are  very  satisfactory  for  rapid  determination.  Cross- 
referencing  avoids  error  in  cases  of  doubt  as  to  the  group  in  which 
a  mineral  actually  falls. 

1.  Hardness  High.  —  Minerals  which  are  distinctly  hard,  .stand 
up  above  most  minerals,  except  quartz,  and  are  scratched  with 
difficulty,  if  at  all,  by  the  needle.     Minerals  from  4.5  to  5.5  in  the 
scale  of  hardness  can  be  grooved  by  a  moderate  pressure  of  the 
needle  point,   but  do  not  show  a  typical  scratch.     Examples: 
pyrite,  magnetite. 

2.  Hardness  Medium.  —  Minerals  which  are  not  scratched  by 
the  weight  of  the  handle  alone,  with  no  extra  pressure  applied,  but 
are  readily  scratched  by  moderate  pressure  on  the  needle.     Ex- 
amples: chalcopyrite,  enargite,  tetrahedrite. 

3.  Hardness   Low.  —  Minerals  easily  scratched   by  the  weight 
of  the  handle  alone.     Examples:  chalcocite,  galena,  bornite. 

MICROCHEMICAL  TESTS 

The  final  determinative  tests  are  microchemical,  as  in  most 
cases  a  mineral  cannot  be  identified  by  its  physical  properties 
alone.  These  separate  the  larger  divisions  into  small  groups  in 
which  any  one  mineral  may  be  readily  identified.  The  method 
of  using  these  tests  has  already  been  described  (p.  30). 

EXPLANATION  OF  TABLES 

Directions  for  Use.  —  The  main  divisions  of  the  classification, 
colored,  white,  and  gray,  are  indicated  by  the  tabs  of  a  thumb  index 
at  the  top  of  the  book.  These  are  the  only  tabs  on  the  upper  margin 


OF  THE  OPAQUE  MINERALS  43 

of  the  page,  all  others  being  on  the  outer  margins.  The  first  step  in 
usirjg  the  tables  is  to  open  them  to  the  beginning  of  one  of  the  main 
divisions,  by  holding  down  with  the  thumb  the  appropriate  tab. 
This  exposes  the  first  subdivision,  marked  by  a  series  of  tabs  on 
the  outer  margin  of  the  right  hand  page.  One  of  these  tabs  is  then 
similarly  held  down,  and  the  tables  opened  to  the  page  carrying 
that  tab,  revealing  the  tabs^of  the  second  subdivision  on  the 
outer  margin  of  the  left  hand  page.  This  procedure  is  continued, 
the  tabs  alternating  from  right  to  left,  until  no  more  new  sets 
appear,  showing  that  the  last  subdivision  has  been  reached.  This 
is  usually  indicated  by  negative  reactions  on  the  left  page  and 
positive  reactions  on  the  right  page;  as,  for  instance,  KCN  neg. 
on  the  left  and  KCN  on  the  right.  (See  pages  116-117.) 

When  this  stage  is  reached,  the  full  descriptions  of  the  desired 
group  of  minerals  will  be  found.  A  mineral  name,  followed  by  a 
reference  to  another  page,  indicates  that  the  mineral  does  not 
properly  belong  in  this  group,  but  its  full  description  may  be 
looked  up  on  the  page  indicated  to  make  entirely  sure  in  doubtful 
cases  that  it  is  not  the  mineral  undergoing  test.  In  running 
down  a  mineral,  the  tables  must  always  be  opened  to  the  page 
which  carries  the  tab  for  the  test  just  made,  and  the  next  test  to 
be  applied  is  indicated  by  the  tabs  on  the  opposite  margin  as  the 
book  is  held  open. 

Examples.  —  One  or  two  examples  will  show  clearly  how  the 
tables  are  intended  to  be  used. 

1.  Suppose  a  mineral  has  been  polished  and  inspected  under 
the  microscope.  It  appears  yellow;  therefore,  hold  down  the 
colored  tab  and  open  to  that  page  (p.  57).  It  is  yellow,  so 
hunt  on  the  right  hand  margin  for  yellow.  Place  the  thumb 
on  this  tab,  and  open  to  that  page  (p.  63).  There  are  no  tabs 
on  the  left,  so  the  mineral  in  question  must  be  found  on  the  pages 
now  open.  The  right  hand  page  is  headed  pale,  the  left  hand, 
bright.  The  mineral  appears  bright  yellow,  so  it  is  sought  on 
the  left  page,  where  are  found  chalcopyrite,  gold,  and  yellowish 
and  orange  "  bornite."  Looking  up  the  reference  to  yellowish 
and  orange  "  bornite,"  one  finds  that  these  are  not  really  bright 
yellow  but  always  orange  or  brownish,  so  they  may  be  eliminated. 
Under  Diff.  in  the  two  minerals  remaining,  it  is  seen  that  they 
are  distinguished  from  each  other  by  color,  behavior  with  KCN 
and  character  of  surface.  The  chemical  test  is  surest  so  KCN 


44  ,      MICROSCOPICAL  DETERMINATION 

is  tried;  it  roughens  and  dissolves  the  surface  of  the  yellow  min- 
eral, thus  proving  it  to  be  gold. 

2.  Taking  a  white  mineral  this  time,  place  the  thumb  on  the 
white  tab,  open  the  book  to  that  page  (p.  81),  and  look  on  the  right 
hand  margin.  Hardness  appears  to  be  the  next  test.  The  min- 
eral appears  smooth,  and  is  easily  scratched  with  a  needle,  showing 
it  to  have  low  hardness.  Place  the  thumb  on  the  tab  hardness 
low,  and  open  to  that  page  (p.  143).  Looking  on  the  left  hand 
margin,  it  is  seen  that  the  outer  tabs  refer  to  color,  compared 
with  galena,  so  the  mineral  is  compared  with  galena  and  found 
to  look  faintly  bluish.  Place  the  left  thumb  on  the  tab  marked 
bluish  white,  and  open  to  the  page  carrying  that  tab  (p.  114). 
Look  on  the  right  again.  The  next  test  is  with  HNO3,  so  make 
that  test,  finding  that  the  mineral  is  attacked  by  HNO3,  noting 
that  it  is  plated  almost  instantly  with  a  film  that  looks  like  metallic 
copper  and  that  part  of  this  film  dissolves  off  quickly,  and  the 
mineral  turns  dark;  in  other  words,  HNO3  gives  a  positive  reac- 
tion, so  hold  down  the  HNO3  tab  and  open  to  that  page  (p.  117). 
There  are  no  more  tabs  on  the  left,  so  the  final  pages  have  been 
reached.  The  left  says  KCN  neg.,  the  right  says  KCN,  so  test  with 
KCN,  finding  that  the  mineral  is  rapidly  etched  and  somewhat 
darkened.  This  puts  it  on  the  right  hand  side  with  a  choice  of 
cuprite,  stromeyerite  and  chalcocite.  The  descriptions  of  these 
minerals  indicate  that  chalcocite  turns  darker  blue  and  effervesces 
with  HN03,  which  rules  it  out;  stromeyerite  does  not  act  with 
HNO3  as  the  mineral  in  question  has  behaved,  whereas  cuprite 
fits  the  case  exactly.  A  final  assurance  may  be  made  by  prov- 
ing that  the  mineral  is  transparent  red  by  oblique  light,  since  chal- 
cocite and  stromeyerite  are  both  opaque. 

These  directions  have  been  made  very  explicit  so  that  there 
shall  be  no  chance  for  mechanical  error  in  using  the  tables.  To 
make  sure  no  mistake  or  omission  has  occurred  in  running  down 
a  mineral,  the  sequence  of  tests  identifying  a  given  group  is  placed 
in  the  upper  corner  of  the  left  hand  page,  so  they  all  may  be  seen 
together,  and  checked  up.  By  this  means,  the  fewest  possible  tests 
need  be  applied,  resulting  often  in  a  considerable  saving  of  time. 
When  the  full  description  of  the  mineral  is  reached,  other  tests  may, 
of  course,  be  applied  to  check  up  the  accuracy  of  the  determination. 

Cross-References.  —  As  previously  explained,  numerous  cross- 
references  have  been  made  in  the  case  of  minerals  on  the  border 


OF  THE  OPAQUE  MINERALS  46 

line  between  two  or  more  colors  or  tints,  or  two  classifications 
of  relief,  or  with  doubtful  chemical  behavior.  That  is,  if  a  min- 
eral might  conceivably,  be  called  either  pale  yellow,  or  cream  colored, 
or  white,  like  pyrite,  for  example,  its  full  description  is  placed 
under  the  heading  cream  and  references  to  this  are  given  in  the 
proper  place  under  each  of 'the  other  two  headings,  so  it  can  be 
found  if  the  observer -assigns  "it  to  any  one  of  these  colors.  Sim- 
ilarly, a  mineral  like  bournonite,  which  is  intermediate  in  hard- 
ness between  minerals  of  medium  and  of  low  relief,  probably 
nearer  medium,  is  fully  described  under  hardness  medium,  and 
a  reference  given  to  this  in  the  appropriate  place  under  hardness 
low.  The  cross-referencing  has  been  especially  complete  among  the 
white  and  faintly  tinted  minerals,  as  here  the  color  differences  are 
very  slight  at  best,  and  some  intermediate  tints  are  indefinite 
even  to  the  practiced  eye. 

Abbreviations.  —  The  abbreviations  on  the  tabs  are  as  follows: 
HN03  is  taken  as  an  example;  abbreviations  for  other  reagents 
may  be  found  on  page  32. 

Abbreviation  Meaning 

HN03.  -  Attacked  by  HN03  (visibly  changed  or  af- 

fected). 

HNO3  neg.  -      Not  attacked  visibly  by  HNO3. 

Fumes  HN03.  —  Tarnished  by  the  fumes  of  HN03  but  not 
visibly  attacked  by  the  liquid,  so  that  a  ring 
of  tarnish  is  formed  around  a  clear  spot, 
which  was  covered  by  the  reagent. 

Eff.    HN03.  —  Attacked  by  HNO3,  with  effervescence. 

No  Eff.HNO3.— Attacked  by  HNO3,  but  without  effervescence. 

In  the  descriptions  of  the  minerals,  the  following  abbreviations 
are  used: 

Col.  —  Color,  including  transparency. 

Occ.  —  Habit  of  occurrence,  if  distinctive  (such  as  platy,  or 
in  crystals  or  crystalline  grains). 

Hard.  —  Hardness. 

Surf.  —  Character  of  polished  surface. 

H.  —  Hardness  as  given  in  Dana's  System  of  Mineralogy; 
supplemented  by  comparison,  where  possible,  with  relative  hard- 
ness to  accompanying  minerals. 


46 


MICROSCOPICAL  DETERMINATION 


Chem.  —  Microchemical  tests. 

Diff.  —  Distinctive   characters,  physical  or  chemical,  which 
serve  to  distinguish  a  mineral  from  others  of  the  group. 
.      -  Negative  test. 

The  following  abbreviations  have  been  found  convenient  for 
designating  some  of  the  commoner  sulphides: 


PY  =  pyrite 
cp  =  chalcopyrite 
bn  =  bornite 
cc  =  chalcocite 
cv  =  covellite 
td  =  tetrahedrite 


en  =  enargite 
si  =  sphalerite 
gn  =  galena 
po  =  pyrrhotite 
mg  =  magnetite 
G=  gangue,   including  all    the 
transparent,  non-metallic 
minerals. 


WHITE/       COLOR£/ 


OUTLINE   OF  THE   CLASSIFICATION 

(Parentheses  around  a  mineral  indicate  a  cross  reference,  and  that  the  full  description 
is  to  be  found  elsewhere  in  the  tables.)  &• 

1.    COLORED 

1.  BLUE 

1.  BRIGHT 

1.  Covellite 

2.  (Chalcocite) 

2.  PALE 

gee:  —  WHITE  —  HARDNESS  Low  —  BLUISH  WHITE. 

2.  PURPLE 

1.  BRIGHT 

1.  Umangite 

2.  Rickardite 

3.  (Purplish  brown  "  bornite  ") 

2.  PALE 

1.  (Purple  "galena") 

2.  (Color adoite) 

3.  YELLOW 

1.  BRIGHT 

1.  Chalcopyrite 

2.  Gold 

3.  (Orange  "bornites") 

2.  PALE 

1.  HNO3NEG. 

1.  Millerite 

2.  (Pyrrhotite) 

3.  (Sulvanite) 

4.  (Chalmersite) 

5.,  (Gold,  var.  electrum) 

2.  HN03 

1 .  (Marcasite) 

2.  (Pyrite) 

.    3.    (Bismuth) 
4.  BROWN 

1.  HNO3NEG. 

1.  Orange  *  bornites" 

2.  (Pyrrhotite) 

3.  (Kalgoorlite) 

2.  HN03 

1.  Purplish  brown  "bornite" 

2.  Sternbergite  —  Frieseite 

3.  Bornite 

4.  Unknown  brown,  Bisbee 

5.  ("  Bronze  enargite  ") 

47 


48  MICROSCOPICAL  DETERMINATION 

5.  PINK 

1.  HNO3NEG. 

1.  (Luzonite) 

2.  (Unknown  pink  —  with  mohawkite) 

2.  HNO3 

1.  KCNNEG. 

1.  Niccolite 

2.  Breithauptite 

3.  (Maucherite) 

4.  (Bismuth) 

2.  KCN 

1.  Copper 

2.  (Bornite) 

3.  (Algodonite) 

4.  (Whitneyite) 

5.  (Cobaltite) 

6.  (Famatinite) 

6.  CREAM 

1.   HARDNESS  HIGH 

1.  HN03NEG. 

1.  Pyrrhotite. 

2.  Unknown  pink  —  with  mohawkite 

2.  HN03 

1.  SURFACE  DULL 

1.  Pyrite 

2.  Marcasite 

2.  SURFACE  SHINY 

1.  Linnseite 

2.  Maucherite 

3.  Hauchecornite 

4.  (Pentlandite) 

5.  (Niccolite) 
2.   HARDNESS  MEDIUM 

1.  HNOsNEG. 

1.  Sulvanite 

2.  Chalmersite 

3.  (Millerite) 

4.  (Unknown,  Butte,  N  13) 

5.  (Pyrrhotite) 

6.  (Delafossite) 

2.  HN03 

1.  "  Bronze  enargite  " 

2.  Algodonite  (Cream) 

3.  Mohawkite  (Cream) 

4.  Whitneyite 

5.  (Pentlandite) 

6.  (Aikinite) 

7.  (Niccolite) 

8.  (Linnaeite) 

9.  (Copper) 

10.   (Hauchecornite) 


WHITE/       COLOR 

^^^^•^•^^•^^•^^^^^  • 


OF  THE  OPAQUE  MINERALS  49 

3.  HARDNESS  Low 

See:  —  WHITE  —  HARDNESS  Low  —  CREAMY  WHITE. 


2.  WHITE 

1.  HARDNESS  HIGH 

1.  HNO  NEG. 

1.  HCL  CONC.  NEG.  t    " 

1.  Rutile 

2.  Ilmenite 

3.  Hematite 

4.  (Pyrrhotite) 

5.  (Franklinite) 

2.  HCL  CONC. 

1.  [  Magnetite 

2.  Sperrylite 

3.  (Unknown  pink  —  with  mohawkite) 

2.  NOEFF.  HNO3 

1.    HCL  UNCHANGED  1' 

1.  No  EFF.  AQ.  REG. 

1.  AQ.  REG.  NEG. 

1.  Cobaltite 

2.  (Linnseite) 

2.  AQ.  REG. 

1.  Glaucodot 

2.  (Pentlandite) 

2.  EFF.  AQ.  REG. 

1.  FECLS  NEG. 

1.  Lollingite 

2.  Ullmannite 

3.  (Arsenopyrite) 

2.  FECLa 

1.  Chloanthite 

2.  Rammelsbergite 

2.    HCL  TURNS  YELLOWISH  GREEN 

1.   Gersdorffite 

3.  EFF.  HNO3 

1.  AQ.  REG.  NEG. 

1.  (Pyrite) 

2.  (Marcasite) 

3.  (Argyropyrite) 

2.  AQ.  REG. 

1.  FECL3  NEG. 

1.  Arsenopyrite 

2.  Kallilite 

3.  Willyamite 

4.  Poly dy mite 

2.  FECL3 

1.  Safflorite 

2.  Smaltite 

3.  Skutterudite 

4.  (Maucherite) 


50  MICROSCOPICAL  DETERMINATION 

2.  HARDNESS  MEDIUM 

1.  GALENA  WHITE 

1.  KOHNEG. 

1.  Chalcostibite 

2.  (Bournonite) 

3.  (Polybasite) 

4.  (Geocronite) 

5.  (Kallilite) 

2.  KOH 

1.  Berthierite 

2.  Guejarite 

2.  CREAMY  WHITE 

1.   No  EFF.  HNO3 

1.  Pentlandite 

2.  (Sulvanite) 

3.  (Chalmersite) 

4.  ("  Bronze  Enargite  ") 

5.  (Berthierite) 

6.  (Linnaeite) 

7.  (Hauchecornite) 
2.  EFF.  HN03 

1.  Argyropyrite 

2.  Aikinite 

3.  (Domeykite) 

4.  (Algodonite,  Cream) 

5.  (Mohawkite,  Cream) 

6.  (Whitneyite) 
,       7.  (Kallilite) 

3.  PINKISH  WHITE 

1.  HN03NEG. 

1.  Luzonite 

2.  (Enargite) 

2.  HNO3 

1.  Famatinite 

2.  (Argyropyrite) 

3.  (Geocronite) 

4.  (Breithauptite) 

4.  GRAYISH  WHITE 

1.   HNO3  NEC. 

1.  KCN  NEC. 

1.  Bournonite 

2.  Tenorite 

3.  Delafossite 

4.  (Tetrahedrite) 

5.  (Regnolite) 

2.  KCN 

1.  (Polybasite) 

2.  (Enargite) 

3.  (Argyrodite) 


WHITE/      COLORIp/ 


OF  THE  OPAQUE  MINERALS  51 


2.  FUMES  HNO3 

1.  KCN  NEG. 

1.  Tetrahedrite 

2.  Tennantite 

3.  Hauerite 

4.  (Bournonite) 

2.  KCN 

!.•*•  Enargite 

3.  HN03 

1.  KCN  NEG. 

1.  Algodonite  (Gray) 

2.  Polytelite 

3.  Alabandite 
4  (Geocronite) 

5.  (Freibergite) 

6.  (Baumhauerite) 

7.  (Mohawkite  gray) 

8.  (Crookesite) 

9.  (Plagionite) 

10.  (Stylotypite) 

11.  (Bournonite) 

2.  KCN 

1.  Mohawkite  (gray) 

2.  Stylotypite 

3.  (Plagionite) 

3.   HARDNESS  Low 

1.   GALENA  WHITE 

1.  PURE  WHITE 

1.  HCLNEG. 

1 .  G  alenobismutite 

2.  Bismuthinite 
3'.  Eucairite 

4.  Tellurium 

5.  Unknown  (white),  Bisbee 

6.  Lehrbachite 

7.  Berzelianite 

8.  Antimonial  Bismuthinite 

9.  (Matildite) 

2.  HCL 

1.  Altaite 

2.  Clausthalite 

3.  Naumannite 

2.  SAME  AS  GALENA  OR  DARKER 

1.  HNO3NEG. 

1.  KOHNEG. 

1.  No  EFF.  AQ.  REG. 

1 .  Jalpaite 

2.  Matildite 

3.  Unknown  (Tonopah) 


52  MICROSCOPICAL  DETERMINATION 

2.   EFF.  AQ.  REG. 

1.  Schirmerite 

2.  Rathite 

3.  Lengenbachite 

4.  Cinnabar 

5.  (Matildite) 

6.  (Polybasite) 

7.  (Bournonite) 
2.   KOH 

1.  Livingstonite 

2.  Stephanite 

3.  Sartor ite 

4.  Dufrenoysite 

5.  (Berthierite) 

6.  (Miargyrite) 
2.  HN08 

1.  KCNNEG. 

1.     HCLNEG. 

1.  FECLS  NEC. 

1.  No  EFF.  HNO3 

1.  Nagyagite 

2.  Freieslebenite 

3.  Guitermannite 

4.  Beegerite 

5.  Jordanite? 

6.  Andorite 

7.  Epiboulangerite 

8.  Unknown  (near  Andorite) 

9.  (Bismuthinite) 

10.  (Lengenbachite) 

11.  (Baumhauerite) 

12.  (Jamesonite) 

2.  EFF.  HNO3 

1.  Boulangerite 

2.  Dognacskaite 

3.  Horsfordite 

4.  Plagionite 

5.  (Chiviatite) 

2.  FECLS 

1.  Arsenic 

2.  "Alloklas" 

3.  Rezbanyite 

4.  Plenargyrite  (hard) 

5.  Schapbachite  (hard) 

6.  Petzite 
2.   HCL 

1.   FECLS  NEG. 

1.  Geocronite 

2.  Meneghinite 

3.  Semseyite 

4.  (Zinkenite) 

5.  (Plagionite) 

6.  (Jamesonite) 


COLORI7 


OF  THE  OPAQUE   MINERALS  53 

2. 


1.  Lillianite 

2.  Galena 

3.  Steinmannite 

4.  Tetradymite? 


2.  KCN      .- 

1.   itermesite 
„      2.   Sti&iite 

3.  Hessite 

4.  (Guejarite) 

5.  (Brogniardite) 

CREAMY  WHITE 

1.   SAME  AS  SILVER,  OR  WHITER 
1.   FECLS  NEG. 

1.  KOHNEG. 

1.  Matildite? 

2.  Guanajuatite 

3.  Chiviatite 

4.  (Bismuthinite) 

5.  (Galenobismutite) 

2.  KOH 

1.   Wittichenite 


1.  No  EFF.  AQ.  REG. 

1.  Hessite? 

2.  Silver 

3.  (Altaite) 

2.  EFF.  AQ.  REG. 

1.   Huntilite 

2.   DARKER  THAN  SILVER 

1.  HNO3  NEG.  . 

1.  Unknown  (creamy,  Butte) 

2.  (Sulvanite) 

3.  (Chalmersite) 

4.  (Berthierite) 

5.  (Gold,  var.  electrum) 

2.  HNO3 

1.   FECLs  NEG. 

1.  Cosalite 

2.  Emplectite 

3.  Metacinnabarite 

4.  Sylvanite 

5.  (Frankeite) 

6.  (Wittichenite) 

7.  (Aikinite) 

8.  (Chiviatite) 

9.  (Freieslebenite) 


54  MICROSCOPICAL  DETERMINATION 

2. 


1.  HCLNEG. 

1.  Melonite 

2.  Calaverite  —  (Krennerite) 

3.  Kalgoorlite 

4.  (Sylvanite) 

5.  (Arsenic) 

6.  (Hessite) 

7.  (Copper) 

8.  (Tapalpaite) 

9.  (Petzite) 

2.  HCL 

1.  Domeykite 

2.  Bismuth 

3.  Dyscrasite 

4.  Tapalpaite 

5.  Chilenite 

6.  (Teallite) 

BLUISH  WHITE. 

1.  HNO3NEG. 

1.  KOH  NEC. 

1.  Tiemannite 

2.  Onofrite 

3.  Polyargyrite 

4.  Stiitzite 

5.  Unknown  (Tonopah) 

6.  (Covellite) 

7.  (Kalgoorlite) 

8.  (Rathite) 

9.  (Cinnabar) 

2.   KOH 

1.  Proustite 

2.  Pyrargyrite 

3.  Unknown,  bluish,  with  Sternbergite 

4.  Vrbaite 

5.  Miargyrite 

6.  (Stephanite) 

2.  HN03 

1.  KCNNEG. 

1.  Purple  "galena" 

2.  Plenargyrite  ("  soft  ") 

3.  Schapbachite  ("soft") 

4.  (Coloradoite) 

2.  KCN 

1.  Cuprite 

2.  Stromeyerite 

3.  (Chalcocite) 

4.  (Polyargyrite) 

5.  (Brogniardite) 


WHITE/       COLORE7 


OF  THE  OPAQUE  MINERALS  55 


4.   GRAYISH  WHITE  i    i  ^ 

1.  HNOaNEG. 

1.  KCNNEG.  '    ;,   : 

1.  Molybdenite 

2.  Regnolite 

3.  Seligmaunite 

4.  "  Argentiferous  Jamesonite  " 

5.  (Cinnabar) 
f5.  (Kalgoorlite) 

7.  (Bournonite) 

8.  (Tiemannite) 

9.  (Rathite) 

10.    (Lengenbachite) 

2.  KCN 

1.  Orpiment 

2.  Argyrodite 

3.  Polybasite 

4.  Pearceite 

5.  (Jalpaite) 

6.  (Miargyrite) 

7.  (Stephanite) 

8.  (Livingstonite) 

2.  HN03 

1.   FECL3  NEG. 

1.  HCL  NEG. 

1.  Stannite 

2.  Baumhauerite 

3.  Realgar 

4.  Crookesite 

5.  (Freieslebenite) 

6.  (Guanajuatite) 

7.  (Andorite) 

8.  (Unknown  —  near  Andorite) 

2.  FUMES  HCL 

1.  Cylindrite 

2.  Frankeite 

3.  Brogniardite 

4.  Jamesonite 

5.  Zinkenite 

3.  HCL 

'  1.    (Alabandite) 
2.    (Cosalite) 


2. 

1.   KCN  NEG. 

1.  Teallite 

2.  Aguilarite 

3.  Petzite? 

4.  Coloradoite 


56  MICROSCOPICAL  DETERMINATION 

2.   KCN 

1.  Chalcocite 

2.  "Tapalpaite"  (gray) 

-3.  (Unknown,  Qrayish,  Butte,  N  13) 

4.  Argentite 

5.  (Stromeyerite) 

6.  (Pearceite) 

3.   GRAY 

1.  HARDNESS  HIGH 

1.  HCL  CONC.  NEG. 

1.  AQ.  REG.  NEG. 

1.  Cassiterite 

2.  Limonite 

3.  Chromite 

4.  (Rutile) 

5.  (Franklinite) 

6.  (Hematite) 

7.  (Ilmenite) 

2.  AQ.  REG. 

1.   Uraninite 

2.  HCL  CONC. 

1.  Franklinite 

2.  Psilomelane 

3.  (Magnetite) 

2.  HARDNESS  MEDIUM 

1.  HCL  NEG. 

1.  Sphalerite 

2.  Wurtzite 

3.  Voltzite 

4.  Erythrozincite 

5.  (Uraninite) 

6.  (Argyrodite) 

2.  HCL 

1.  Cuprodescloizite 

2.  (Cuprite) 

3.  (Alabandite) 

4.  (Tenorite) 

5.  (Delafossite) 

3.  HARDNESS  Low 

1.  Lorandite 

2.  (Stannite) 

3.  ("Petzite?") 

4.  (Argyrodite) 

5.  (Erythrozincite) 

6.  ("  Tapalpaite  "  gray) 


COLORED 


TABLES  FOR  MINERAL  IDENTIFICATION 


57 


COLORED 
BLUB 


Bright 


COVELLITE  CuS 

COL.  Blue.  Varies  from  deep  bright  blue,  sometimes  purple,  to  very 
pale  blue,  almost  white,  like  chalcocite. 

Occ.  Usually  in  minute  plates  appearing  as  needles  in  section,  some- 
times even  feathery  aggregates.  Rarely  in  large  plates,  up  to  two 
inches  across. 

HARD.     Low.  SURF.    Smooth.'  H.  1.5-2   j  >  ££rnite 

CHEM.    1.  HNOs .    2.  HNOs  cone. .    3.  KCN.    Instantly  deep 

violet,  rapidly  darker;  rubs  off,  leaving  a  yellowish  coating  and 
rough  surface.  4.  HC1 .  5.  HC1  cone. .  6.  Aq.  Reg.  In- 
stantly effervesces  a  short  time,  then  stops;  turns  pinkish  where 

bubbles  started;  rubs  clean  easily.    7.  FeCls .    8.  KOH .    9. 

NaOH .    10.  (NH4)2SX .     11.  AgNO3  3  per  cent .    Quickly 

plated  with  silver,  persistent.     12.  K4Fe(CN)8 .     13.  Iodine . 

14.  KaFe(CN)..     Slowly  greenish,  persistent.     15.  NH4OH . 

DIFF.     Col.     Chem.  1. 

NOTE.  Covellite,  observed  in  plane  polarized  light,  is  pleochroic, 
dark  blue  (parallel  to  the  plane  of  vibration  of  the  nicol) ,  to  light 
blue  (perpendicular  to  this).  Sections  which  appear  dark  blue 
in  ordinary  light  do  not  change  color  in  polarized  light. 


CHALCOCITE         See  page  107. 


58 


WHIT 


Pale 


See  WHITE.     HARDNESS  Low.     BLUISH  WHITE,  pp.  114-117. 

Many  pale  blue  minerals  are  transparent  red  with  oblique  illumination, 


9 


£ 


i 


I 

o 


a 


59 


< 

tu 
^ 
u 


COLORED 
PURPLE 


Bright 


UMANGITE  CtuSej 

COL.     Bright  reddish  purple,  very  close  to  Rickardite. 

HARD.     Low.  SURF.     Smooth.  H.  3. 

CHEM.     1.  HNO3.     Turns  bluish,  persistent.     2.  KCN .     3.  HC1. 

Turns  bluish,  persistent.     4.  Aq.  Reg.     Turns  a  little  bluish;   rubs 

to   original    color.     5.    FeCls.     Turns  bluish,  persistent.     6.  KOH. 

Slowly  coated  with  brown;    rubs  easily  to  bluish.     7.    (NH4)2SX. 

Turns  bluish;   rubs  to  light  blue. 
DIFF.     Col.     Chem.  1. 


RICKARDITE  Cu4Tes 

COL.  Bright  reddish  purple,  almost  red,  slightly  brighter  than  umang- 
ite.  Microscopically  mottled,  with  bluish  and  yellowish  patches 
mixed. 

HARD.     Low.  SURF.     Smooth.  H.  3.5. 

CHEM.  1.  HNOs.  Instantly  effervesces  and  blackens.  2.  KCN. 
Faintly  bluish. 

DIFF.     Col.     Chem.  1. 


PURPLISH  BROWN  "  BORNITE  "        See  page  65. 


60 


WHITE/ 


Pale 


PURPLE  "  GALENA  »        See  page  116. 


COLORADOITE        See  page  106. 


COLORED 
YELLOW 


Bright 


CHALCOPYRITE  CuFeSa 

COL.     Bright  brass  yellow.     Sometimes  appears  pale,  by  association 

with  colored  minerals. 

HARD.     Medium.  SURF.     Smooth.  H.  3.5-4  =  bn. 

CHEM.     1.  HNps .    2.  HNO3.    Hot.     Tarnishes  the  mineral  bright 

colors,  then  dissolves  it.     3.  HNO3  cone.     Turns  deep  yellow;  rubs 

off.     4.  KCN (but  occasionally  develops  structure).      5.  HC1 . 

6.  HC1  cone. .     7.  HC1.    Hot,  same  as  hot  HNO3.     8.  Aq.  Reg. 

Tarnished  iridescent.     9.  FeCls .     10.  KOH .     11.  NaOH . 

12.     (NH4)2Sx .      13.    K4Fe(CN)6 .     14.    KsFe(CN)6 .      15. 

Iodine . 

DIFF.     Col.     Surf.     Chem.  4. 


GOLD  Au 

COL.     Golden  yellow,  richer  than  chalcopyrite,  and  usually  deeper. 
HARD.     Low.  SURF.     Smooth,  metallic.  H.  2.5-3. 

CHEM.     1.     HNO3 .     2.     HNO3     cone. .     3.     KCN.     Quickly 

darkens  and  produces  rough  surface;    sometimes  develops  structure. 

4.  HC1 .     5.  HC1  cone. .    6.  Aq.  Reg. .    7.  FeCl3.    A  little 

pale  and  tarnished    (?) ;   rubs   off   very   easily.      8.    KOH .     9. 

NaOH .     10.  (NHOaSx .     11.  K4Fe(CN)6 .     12.  KsFe(CN)« 

.     13.  Iodine . 

DIFF.     Col.     Surf.     Chem.  3. 

NOTE.  Gold  is  variable  in  color,  according  as  it  is  alloyed  with 
silver.  Electrum  is  very  pale  yellow.  A  very  good  test  for 
small  pieces  of  gold  is  to  amalgamate  by  rubbing  on  a  mercury 
covered  chamois  skin.  The  gold  will  turn  bright  white.  (F.  C. 
Lincoln  devised  this  test.) 


YELLOWISH  AND  ORANGE  "  BORNITES  "        See  page  64. 


62 


WHITER 


Pale 


HNOtNeQ 

m 


MILLERITE  NiS 

COL.     Very  pale  yellow. 

HARD.     Medium.  SURF.     Smooth.  H.  3-3.5  <po. 

CHEM.     1.    HNOa .     2.    HNO3    cone.     Quickly    bright    yellowish 

brown;   rubs  off  easily  to  very  pale.     3.  KCN .      4.  HC1 .     5. 

HC1  cone. .     6.  Aq.  Reg.     Slowly  bright  brown;  fumes  tarnish 

brown;  rubs  clean  easily.    7.  FeCla .     8.  KOH .     9.  NaOH . 

10.    (NH4)2SX .     11.    K4Fe(CN)« .      12.    KaFeCCN), .      13. 

Iodine . 

DIFF.     Col.     Chem.  2,  6. 


PYRRHOTITE         See  page  76. 
SULVANITE         See  page  72. 
CHALMERSITE         See  page  72. 
GOLD  (var.  electrwri)         See  page  62. 


o 
tt 


HNOi 


MARCASITE         See  page  78. 
PYRITE         See  page  78. 
BISMUTH         See  page  125. 


63 


EC 

C* 

u 


COLORED 
BBOWN 


HNOs  Neg. 


UNKNOWN  MINERAL  "  Orange  Bornite  " 

A  group  of  unknown  minerals,  ranging  in  color  from  orange  yellow  to 
bright  yellowish  brown,  occurring  in  small  bits  in  bornite  ores.  Ap- 
parently not  affected  by  HNOs,  but  all  reactions  obscured  by  pres- 
ence of  easily  soluble  bornite.  Usually  resistant  to  enriching 
solutions. 


PYRRHOTITE         See  page  76. 
KALGOORLITE         See  page  124 


64 


WHITER 


HNO, 


UNKNOWN  MINERAL  Ejirplish  brown  "  Bornite  " 

COL.     Purplish  brown.     With  bornite,  distinctly  purplish. 

HARD.     Low.  SURF.     Smooth.  H  =  bn? 

CHEM.     1.  HNOs.     Dissolves  readily  with  effervescence,  leaving  rough 

surface,  pale  gray  or  pinkish  (more  vigorous  than  ordinary  bn). 
DIFF.     Col.     Chem.  1. 

NOTE.     May  be  argentiferous  bornite,  as  it  occurs  with  silver 
minerals  and  native  silver  in  the  two  specimens  studied. 


STERNBERGITE-FRIESEITE  Ag2Fe6S8  or  AgFe2S3 

COL.     Pale  yellowish  brown.    With  bornite,  pale  yellowish  brown,  no 

pink. 

HARD.     Low.  SURF.     Smooth.  H.  1-1.5. 

CHEM.     1.  HNOs.     Quickly  bright  iridescent;  rubs  to  persistent  gray. 

2.  KCN .     3.  HC1 .     4.  Aq.  Reg.     Faint  brown.     5.  FeCh . 

6.  KOH     Quickly  bright  brown,  rubs  off. 
DIFF.     Col.     Chem.  1,  2.    - 


BORNITE  Cu5FeS4 

COL.     Pinkish  brown. 

HARD.     Low.  SURF.     Smooth.  H.  3  <  cp. 

CHEM.  1.  HNOs.  Quickly  golden  brown,  with  effervescence,  occasion- 
ally developing  "cleavage."  2.  HNOs  cone.  Effervesces,  tarnishes 
bright  reddish  brown,  which  rubs  off,  showing  fine-grained  "cleav- 
age." 3.  KCN.  Quickly  brown,  developing  "cleavage,  "like  HNOa. 

A  more  dilute  sol.  (3  per  cent)  produces  coarser  etching.  4.  KC1 . 

5.  HC1  cone. 6.  Aq.  Reg.  Instantly  effervesces  and  etches 

slightly ;  turns  pale  yellowish  brown ;  fumes  tarnish  dark  brown  and 

iridescent.  7.  FeCls .  Boiled  with  5  per  cent  sol.  a  few  minutes, 

etches  better  than  KCN.  8.  KOH .  9.  NaOH .  10.  (NH4)2SX. 

Quickly  blue  and  iridescent,  rubs  off  easily.  11.  H2SO4  cone. . 

12.  NH4OH .  13.  KsFe  (CN)6.  Very  bright,  uniform  brown, 

rubs  off  fairly  easily.  14.  K4Fe(CN)6  +  HC1  cone.  Brilliant  iri- 
descent, persistent.  15.  Iodine.  Dissolves  slightly. 

DIFF.     Col.     Chem.  1. 

NOTE.     Color  varies  very  slightly,  from  yellower  to  pinker  brown. 


UNKNOWN  MINERAL  (Brown,  from  Bisbee) 

COL.  Pale  coffee  brown.  With  bornite,  pale  grayish,  yellowish, 
brown,  no  red;  with  stern bergite,  faintly  grayer  brown,  very  close; 
with  "orange  bornite"  slightly  creamier  brown,  no  red. 

HARD.     Medium  or  low.    SURF.     Smooth.  H  >  bn.   =  cp. 

CHEM.  1.  HNOs.  Rather  quickly  tarnished  slightly  darker  brown; 

rubs  off  easily.  2.  KCN .  3.  HC1 .  4.  Aq.  Reg. (or 

slowly  tarnished,  with  slight  effervescence.  Reaction  may  be  modi- 
fied by  the  presence  of  bornite).  5.  FeCls .  6.  KOH . 

DIFF.     Col.     Chem.  1,  2. 


BRONZE  ENARGITE         See  page  74. 


65 


COLORED 

PINK 

HNOi 


KCN  Neg. 


NICCOLITE  NiAs 

COL.  Creamy  pink.  With  galena,  distinctly  pinkish  cream;  with 
maucherite,  pale,  decidedly  yellowish  brown;  with  copper,  pale 
yellowish  brown;  with  whitneyite,  deep  pinkish  cream. 

HARD.     High.  SURF.     Shiny,  pitted.  H.  5-5.5. 

CHEM.  1.  HNOs.  Instantly  effervesces,  darkens  and  etches.  Coated 
with  white  flocculent  precipitate.  Rubs  off  clean  to  show  etched 

surface.     2.  KCN .     3.  HC1 .     4.  HC1  cone. .      5.  Aq.  Reg. 

Slowly    brown,  with    moderate    effervescence.     6.    FeCls .     7. 

KOH .     8.  NaOH .     9.  (NHO«SX .     10.  NH4OH .     11. 

K3Fe(CN)6 .         12.     K4Fe  (CN)« .      13.   Iodine . 

DIFF.     Col.     Chem.  1,  6. 

NOTE.  Niccolite  with  Sb  shows  intergrown  breithauptite,  or  some 
other  mineral,  and  does  not  appear  to  grade  chemically  into  breit- 
hauptite. 


BREITHAUPTITE  NiSb 

COL.  Pink.  With  copper,  very  pale  pink,  no  yellow  tinge;  with 
niccolite,  pink,  with  no  yellow  tinge. 

HARD.     Medium.  SURF.     Smooth.  H.  5.5  niccolite. 

CHEM.  1.  HNOa.  Quickly  blackens  and  tarnishes;  black  persistent. 
2.  KCN .  3.  HC1 .  4.  HC1  cone- .  5.  Aq.  Reg.  In- 
stantly effervesces,  slowly  turns  brown  and  etches;  rubs  to  per- 
sistent brilliant  iridescent.  6.  FeCla.  Rapidly  darkens;  rubs  clean, 

showing  pitted  surface.  7.  KOH .  8.  (NH4)2SX .  9.  NH4OH 

.  10.  Iodine .  11.  KsFeCCN). .  12.  K4Fc(CN)6 . 

DIFF.     Col.     Chem.  6. 


MAUCHERITE        See  page  79. 
BISMUTH         See  page  125. 


I 


66 


WHITE/ 


KCN 


COPPER  Cu 

COL.  Pink."  With  bornite,  bright  pink;  with  breithauptite,  de- 
cidedly yellowish  pink. 

HARD.     Medium.         SURF.     Metallic,  smooth.  H.  2.5-3  >  cc. 

CHEM.  1 .  HNOs.  Dissolves  rapidly,  but  merely  roughens,  and  does  not 
change  color.  2.  HNOs  cone.  Instantly  dissolves,  tarnishes  bright 
iridescent,  shows  crystal  (?)  structure.  Fumes  tarnish  iridescent, 
persistent.  3.  KCN.  Slowly  tarnishes  brown;  rubs  off  to  show 

very  fine-grained  solution  surface.  4.  HC1 .  5.  HC1  cone. 

Tarnishes  slightly.  6.  Aq.  Reg.  Blackens  rapidly ;  rubs  black  and 
smooth.  7.  Feds.  Instantly  blackens  and  makes  a  solution  pit.  On 
washing  off,  the  dilute  solution  tarnishes  copper  brilliant  red,  which 
rubs  off.  8.  KOH.  Slowly  tarnished  bright  brown,  then  red,  then 
bright  blue,  persistent.  9.  (NH^Sx.  Instantly  blackens,  persistent. 
Fumes  tarnish  brilliant.  10.  NaOH.  Turns  light  reddish  brown, 
persistent.  11.  Iodine.  Makes  white  coating,  which  rubs  off  very 
easily,  showing  roughened  surface  below. 

DIFF.     Col.     Surf. 


BORNITE         See  page  65. 
ALGODONITE         See  page  74. 
WHITNEYITE         See  page  75. 
COBALTITE         See  page  86. 
FAMATINITE         See  page  99. 


UJ 

u 
u 


COLORED 
PINK 
HN03  NBQ. 


I 
I 


LUZONITE         See  page  98. 

UNKNOWN  PINKISH  MINERAL  (in  Mohawkite)         See  page  76. 


WHITER 


I 


ot 
u 


COLORED 
CREAM 
HARDNESS  Low 


See  WHITE.    HARDNESS  Low.    CREAMY  WHITE,  pp.  118-127. 


70 


WHITER 


» 

* 


cu 

u 
u 


COLORED 
CREAM 

HARDNESS  MEDIUM 
HNO3  NEG. 


SULVANITE  CuaVS* 

COL.     Cream.     With  galena,  very  pale  lemon  yellow,  almost  cream; 

with  silver,  pale  yellowish  cream. 

HARD.     Medium.                SURF.     Smooth.                                    H.  3.5. 
CHEM.     1.  HNOs .     Fumes  tarnish ;  rubs  clean  easily.     2.  KCN . 

3.  HC1 .     4.  Aq.  Reg.     Tarnishes  bright  brown,  rubs  clean  easily. 

5.  FeCla .     6.  KOH . 

DlFF.       Col. 

CHALMERSITE  CuFe2S8 

COL.     Cream.     With  galena,   decidedly  cream  colored;    with  chal- 

copyrite,  pale  cream;  with  calaverite,  decidedly  yellower. 
HARD.     Medium.  SURF.     Smooth.  H.  3.5    >  cp. 

CHEM.     1.    HNO3 .     Fumes    tarnish    slightly.     2.    KCN .      3. 

HC1 .     4.  Aq.  Reg.     Effervesces  slightly;    instantly  bright  iri- 
descent, rubs  clean  easily.     5.  FeCla .     6.  KOH . 

5?  DIFF.     Col. 

M 


!5J  MILLERITE         See  page  63. 

C/}  UNKNOWN  CREAMY  MINERAL  (Butte,  N  13)         See  page  126. 

§ 

Q  PYRRHOTITE         See  page  76. 

or 

3  DELAFOSSITE         See  page  92. 


S 

a 


5 

72 


WHITE 


¥ 

2 
O 


0 

2 

E 


73 


I 


COLORED 

CREAM 

HARDNESS  MEDIUM 

HNO« 


BRONZE  ENARGITE  (CuSn),  (SbAs),  S    ? 

COL.     Cream.     With  pyrrhotite,  same;    with  galena,  pale  brownish 

cream;   with  silver,  pale  brownish  cream. 

HARD.     Medium.  SURF.     Shiny.  H.   =  en. 

CHEM.    1.  HNOs.    Very  slowly  bright  brown.    2.  HNOs  cone.    Rather 

quickly  brown,  gradually  turning  brighter  and  iridescent.     Rubs 

easily  to  very  faint  brown,  often  showing  a  little  structure  (?).     3. 

KCN.    Solution  slowly  turns  purplish  red,  increasing  in  intensity. 

Mineral  is  slightly  etched,   but  does  not  develop   structure.     4. 

HC1  -  .      5.  HC1  cone.  -  .      6.  Aq.  Reg.      Quickly  bright  brown 

iridescent;     rubs    clean    easily.     7.    FeCls  -  .     8.    KOH  -  .     9. 

NaOH  -  .     10.  NH4OH  -  .      11.  Iodine  -  .     12.  K4Fe(CN)6  -  . 

13.  KsFe  (CN)6  -  . 
DIFF.     Chem.  3. 

NOTE.      Contains  Cu,   Sn,  Sb,   As,  S.    Probably  analogous  to 
enargite  in  composition,  but  with  different  crystal  form. 


ALGODONITE  (CREAM)  Cu,As     (?) 

COL.  Cream.  With  galena,  pale  pinkish  cream;  with  whitneyite, 
pale  cream;  with  mohawkite  (cream),  same. 

HARD.     Medium.  SURF.     Smooth.  H.  4. 

CHEM.  1.  HNOs.  Instantly  blackens  with  effervescence,  leaving  a 
rough  surface.  2.  KCN.  Slowly  brown,  with  slight  effervescence. 
Rubs  to  pale  gray  and  shows  structure.  3.  HC1  -  .  4.  Aq.  Reg. 
Effervesces  slightly  and  darkens  and  etches.  5.  FeCls.  Instantly 
blackens.  6.  KOH.  Rapidly  iridescent.  7.  (NH4)2SX.  Instantly 
bright  iridescent.  8.  Iodine.  Turns  gray.  9.  NH4OH.  Slowly  pale, 
even,  brown.  10.  K4Fe(CN)6.  Tarnished  gray,  rubs  off.  11. 
K3Fe(CN)6.  Faint  brown,  rubs  off. 

DIFF.     Chem.  3,  6. 


MOHAWKITE  (CREAM)  CusAs  (with  Ni  and  Co) 

COL.     Cream.     With  galena,  pale  pinkish  cream;    with  algodonite 
(cream),  same. 

HARD.     Medium.  SURF.     Smooth.  H.  4. 

CHEM.    1.  HNOs.    At  once  black,  with  violent  effervescence.    2.  KCN. 

Dissolved  and  turned  brown;  rubs  off  pale.     3.  HC1 (when  with 

an  unknown,  harder  mineral,  blackens).  4.  HC1  cone.  Same  as 
3.  5.  Aq.  Reg.  Same  as  3.  6.  FeCls.  Instantly  blackens,  develops 

structure  (?)     7.    KOH .     8.    (NH4)2SX.     Instantly  yellow.     9. 

KsFe(CN)e.  Slowly  brilliant  persistent  tarnish;  dissolves  visibly. 
10.  K4Fe(CN)e.  Slowly  faint  tarnish,  forming  persistent  ring.  11. 
Iodine.  Turns  bluish  gray. 

DIFF.     Col.     Chem.  3,  7. 

NOTE.     May  be  about  the  same  as  algodonite  cream. 


WHITNEYITE  Cu»As 

COL.  Cream.  With  galena,  rather  deep  pinkish  cream ;  with  maucher- 
ite,  pale  brownish  cream;  with  niccolite,  cream;  with  copper,  very 
pale  yellowish  brown. 

HARD.     Medium.     SURF.     Smooth,  but  apt  to  be  finely  pitted.    H.  3.5. 

CHEM.  1.  HNOs.  Effervesces  violently,  and  rapidly  turns  bright  brown. 
Dissolved.  2.  KCN.  Quickly  dark  brown;  rubs  to  gray,  showing 
structure.  3.  HC1.  Tarnishes  instantly;  rubs  clean.  4.  Aq.  Reg. 
Instantly  blackens  and  dissolves;  develops  structure.  5.  FeCls. 
Instantly  blackens;  rubs  to  dark  gray.  6.  KOH.  Tarnishes  quickly 
bright  yellow,  then  brown.  7.  NH4OH.  Slowly  deep  yellowish  brown, 
rubs  to  very  faint  purplish  tinge.  8.  (NH4)2SX.  Instantly  iridescent ; 
rubs  to  dark  gray.  9.  KsFe(CN)g.  Instantly  brown;  rubs  clean  very 
easily.  10.  K4Fe(CN)«.  Faint  brown,  rubs  clean.  11.  Iodine,  dark 
gray  iridescent. 

DIFF.     Col.     Chem.  3,  6. 


WHITE 


PENTLANDITE         See  page  100. 
AIKINITE        See  page  10  lv 
NICCOLITE         See  page  66. 
LINN-EITE         See  page  79. 
COPPER         See  page  67. 
HAUCHECORNITE         See  page  79. 


6 

z 

K 


75  < 

m 

& 
o 


COLORED 
CREAM 

HARDNESS  HIGH 
HNO3  NEQ. 


PYRRHOTITE  FeS(S)x 

COL.  Cream.  With  galena,  very  pale  brown;  with  silver,  very  pale 
brownish  cream;  with  arsenopyrite,  very  pale  creamy  brown. 

HARD.     High.  SURF.    Shiny  but  pitted.  H.  3.5-4.5  ;»  cp. 

CHEM.  1.  HNOs  -  .  Slowly  very  faint  brown.  Fumes  tarnish 
slightly.  2.  HNO3  cone.  -  ?  3.  KCN  -  .  4.  HC1  -  .  Fumes 
quickly  tarnish.  5.  HC1  cone.  -  .  6.  Aq.  Reg.  Effervesces  slowly, 
turns  quickly  brilliant  iridescent  in  centre  of  drop,  and  brown  near 
edges.  Fumes  instantly  tarnish  brown.  Rubs  off  easily  to  pale 
brown.  7.  FeCls  -  .  8.  KOH.  Slowly  tarnishes  brilliant  irides- 
cent colors,  persistent.  9.  NaOH,  same  as  KOH.  10.  (NH^zSx  -  . 
11.  K4Fe(CN)6  -  .  12.  K3Fe(CN)8  -  .  13.  Iodine  --  .  14.  Hot 
HC1  tarnishes  quickly  bright  colors,  different  on  different  grains, 
then  blackens  and  dissolves. 

DIFF.     Col.     Chem.  6  and  14. 

NOTE.     Practically  constant  in  color,  though  variable  in  sulphur 
content. 


UNKNOWN  MINERAL  (pinkish,  in  Mohawkite)         ? 

COL.     Pale  pinkish  cream.     With  galena,  very  pale  brown  or  cream, 

with  a  tinge  of  pink;  with  maucherite,  about  same  color. 
HARD.     High.  SURF.     Shiny,  pitted.  H.  >  mohawkite. 

CHEM.     1.    HNOs .     Fumes    tarnish    slightly.     2.    KCN .     3. 

HC1 .     4.    HC1  cone. .      5.    Aq.  Reg. .      6.    FeCla .     7. 

KOH . 

DIFF.     Col.     Chem.  6. 

NOTE.  Some  of  the  apparent  inertness  of  this  mineral  may  be 
due  to  the  fact  that  it  occurs  surrounded  by  the  readily  attacked 
mohawkite,  which  may  obscure  or  retard  any  reaction.  Its 
presence  certainly  affects  some  of  the  reactions  of  the  mohawk- 
ite. 
The  mineral  may  carry  much  Ni  or  Co,  but  this  cannot  be  proved. 


s 

C/) 

I 

1 


WHITE 


o 

z 

E 


0 

z 

B 


77 


< 

UJ 
^ 
0 


s 

J^<  COLORED 

Hj  CREAM 

HARDNESS  HIGH 
f/i  HNO3 


Surface  Dull 


s 


I 

i 


PYRITE  FeSj 

COL.     Cream.     With  galena,  pale  creamy  yellow;  with  arsenopyrite, 

pale  yellow. 
Occ.     Rounded  or  irregular  grains,  or  in  crystals,  practically  always 

the  oldest  sulphide  present. 

HARD.     High.  SURF.     Scratched  and  dull.  H.  6-6.5. 

CHEM.     1.  HNO3.     Slowly  faint  brown,  with  very  slow  effervescence. 

Persistent.     2.  HNO3  cone.     Same.      3.  KCN  -  .     4.  HC1  -  .     5. 

HC1  cone.  -  .     6.   Aq.    Reg.  -  .     7.  FeCls  -  .     8.  KOH  -  .     9. 

NaOH  -      10.     K4Fe(CN)6  --  .      11.     K3Fe(CN)8  -  .       12.     Io- 

dine -  .     13.    (NH^Sx.     Slightly  tarnished  ordinarily,  but  with 

enargite,  rather  brightly  tarnished. 
DIFF.     Hard.     Occ.     Col.     Chem.  1. 


MARCASITE  FeSa 

COL.  Cream.  With  galena,  pale  creamy  yellow;  with  silver,  creamy 
white;  with  arsenopyrite,  decidedly  yellowish;  with  pyrite,  slightly 
paler  (usually)  ;  with  millerite,  paler  and  browner. 

Occ.     Frequently  in  radial  growths,  or  intergrown  with  pyrite. 

HARD.     High.  SURF.    Scratched  and  dull.         H.  6-6.5  =  pyrite. 

CHEM.  1.  HNOs.  Slowly  effervesces,  and  turns  brown  to  black,  slowly; 
persistent.  2.  HNO3  cone.  Same.  3.  KCN  -  .  4.  HC1  -  .  5. 
HC1  cone.  --  .  6.  Aq.  Reg.  Very  slowly  faint  brown,  persistent. 
7.  FeCl3  -  .  8.  KOH  -  . 

DIFF.     Col,     Chem.  1. 


78 


WHITE 


Surface  Shiny 


LINN^EITE  COsS, 

COL.     White.     With  galena,  pale  pinkish  creamy  white;   with  silver, 

very  pale  brownish  cream;    with  arsenopyrite,  very  pale  pinkish 

cream. 

HARD.     High.      SURF.     Shiny  but  usually  pitted.  H.  5.5  ;»  cp. 

CHEM.     1.  HNOs.    Very  faintly  brownish;  fumes  slowly  tarnish  brown. 

2.  KCN  -  .     3.  HC1  -  .     4.  HC1  cone.      Slowly  very  faint  brown. 

5.  Aq.  Reg.  -    Fumes  tarnish  slightly.    6.  FeCls  -  .    7.  KOH  -  . 

8.  NH4OH  --  . 
DIFF.     Col.     Chem.  1. 


MAUCHERITE  Ni3As2 

COL.  Cream.  With  galena,  faintly  pinkish  cream;  with  silver,  same 
as  with  galena;  with  niccolite,  very  pale  gray;  with  whitneyite,  pale 
grayish  cream;  with  arsenopyrite,  pale  pink. 

HARD.     High.  SURF.     Shiny,  pitted.  H.  5. 

CHEM.  1.  HNOs.  Effervesces  vigorously,  and  blackens  almost  im- 
mediately, rubbing  clean  to  show  roughened  surface.  2.  KCN . 

3.  HC1 .  4.  HC1  cone. .  5.  Aq.  Reg.  Slowly  brown,  with 

moderate  effervescence.  6.  FeCls.  Slowly  faint  brown,  rather  per- 
sistent. 7.  KOH .  8.  (NH4)2SX .  9.  NH4OH .  10. 

K4Fe(CN)6 .  11.  K3Fe(CN)6.  Pale  brown  iridescent  tarnish, 

rubs  off  clean. 

DIFF.     Col.     Chem.  1,  6. 


HAUCHECORNITE  (NiCo)7(Bi,S,Sb)8 

COL.     Cream.     With    galena,    rich    cream    color;     with     pyrrhotite 

slightly  less  yellow,  more  of  a  pink  tinge;   polishes  smoother,  but  is 

very  close;   with  millerite,  purplish  gray. 

HARD.     High-medium.       SURF.     Smooth.  H.   =  5  ?  >  millerite. 

CHEM.     1.  HNOs.    Very  slowly  brown.    Fumes  tarnish  slightly.    Rubs 

clean  easily,  leaving  a  slightly  etched  surface.     2.   KCN .      3. 

HC1 .     Fumes  tarnish  slightly.     4.  Aq.  Reg.     Quickly  turns  bright 

brown,  fumes  tarnish  slightly.     Rubs  clean  very  easily.    5.  FeCls . 

6.  KOH . 

DIFF.    Chem,  4. 


PENTLANDITE         See  page  100.  Q 

z 

NICCOLITE         See  page  66.  J3 


79 


WHITE 

HARDNESS  HIGH 
EFF.  HNOi 
AQ.  REG.  NEG. 


ARGYROPYRITE        See  page  101. 
MARCASITE        See  page  78 
PYRITE        See  page  78. 


! 


80 


WHITE 


E 

O 

£ 
v) 

s 

i 


i 

5 


o 


! 


UJ 
Q 


81 


WHITB 

HARDNESS  HIGH 
EFF.  HNOi 
AQ.  REG. 


FeCla  Neg. 


ARSENOPYRITE  FeAsS 

COL.  White.  With  galena,  pale  cream;  with  silver,  almost  white, 
slightly  creamy;  with  chloanthite,  pale  yellowish  white. 

HARD.     High.     SURF.     Scratched  and  dull  usually.     H.  5.5-6  <  py? 

CHEM.  1.  HNOs.  Quickly  darkens  (with  effervescence)  through  iri- 
descent colors  to  deep  brown,  with  rough  surface.  2.  KCN .  3. 

HC1 .     4.  HC1  cone .     5.  Aq.  Reg.    Slowly  dark  brown,  with 

slight  effervescence.     6.  FeCla .     7.  KOH .     8.  NH4OH . 

DIFF.     Col.     Chem.  1,  6. 

NOTE.     Sometimes    reaction    1    goes    quite    slowly.     Gives    off 
arsenic  odor  when  ground  on  coarse  wheel. 

KALLILITE  NiBiS(Sb,  As) 

COL.     White.     With  galena,  very  pale  creamy  white. 

HARD.     High  (medium).  SURF.     Smooth.  H.  >  cp. 

CHEM.  1.  HNOs.  Quickly  tarnishes  iridescent.  Effervesces  slowly, 
darkens.  Coated  with  white,  some  parts  more  than  others. 

Rubs  off  to  show  gray,  etched  surface.     2.  KCN .      3.  HC1 . 

4.  Aq.  Reg.  Instantly  effervesces,  turns  slowly  brown,  darker  where 
bubbles  formed,  and  fumes  tarnish  brown  instantly.  Rubs  clean, 
showing  etched  surface.  5.  FeCls .  6.  KOH . 

DIFF.     Surf.     Chem.  1,  4. 

NOTE.     Very  like  willyamite,  but  softer? 

WILLYAMITE  (CoNi)SbS 

COL.     White.     With  galena,  pale  creamy  white. 

HARD.     High.  SURF.     Shiny,  pitted. 

CHEM.  1.  HNOs.  Instantly  bright  iridescent,  then  slowly  dark  brown. 
Slight  effervescence.  Coated  with  white.  Rubs  to  gray  etched 
surface.  2.  KCN .  3.  HC1 .  4.  Aq.  Reg.  Instantly  effer- 
vesces, then  slowly  turns  light  brown,  darker  where  bubbles  formed. 
Rubs  clean  easily,  leaving  practically  no  trace  of  etching.  5. 
FeCls .  6.  KOH . 

DIFF.     Surf.     Chem.  1,  4. 

NOTE.     Very  like  kallilite,  but  harder? 

POLYDYMITE  Ni4S. 

COL.  White.  With  galena,  pale  creamy  white;  with  arsenopyrite 
practically  pure  white;  with  rammelsbergite,  very  pale  pink. 

HARD.     High.          SURF.     Shiny  but  pitted.  H.  4.5  >  cp. 

-^®  CHEM.     1.  HNOs.     Slowly  bright  iridescent  with  slow  effervescence. 

JO  Develops  crystal  structure.     2.  KCN .     3.  HC1 acid  turns 

i^  bright  yellowish  green.     4.  HC1  cone.     Same  as  HC1.     5.  Aq.  Reg. 

V*  Very  slowly  brown  with  slow  effervescence.     Acid  turns  greenish 

*"•«  yellow.     Fumes  tarnish  slightly.     6.  FeCls .     7.  KOH .    8, 

f  .  NH4OH . 

U,  DIFF.     Chem.  1. 


82 


SAFFLORITE  CoAs2 

COL.  White.  With  galena  and  silver,  pure  white;  with  arsenopyrite, 
pure  white;  with  smaltite,  pure  white. 

HARD.     High.  SURF.     Shiny  but  pitted.  H.  4.5-5  <  py. 

CHEM.  1.  HNOs.  Effervesces  and  blackens  quickly.  Rubs  clean  to 
show  roughened  surface.  2.  KCN  -  .  3.  HC1  -  .  4.  HC1 
cone.  -  .  5.  Aq.  Reg.  Slow  effervescence,  increasing  in  amount. 
Mineral  slowly  turns  faint  brown,  acid  turns  yellowish  green.  Rubs 
off  to  very  faint  brownish  stain.  6.  Feds.  Very  slowly  tarnishes 
bright,  and  rubs  off  to  show  differential  etching  along  crystal  direc- 
tions. 7.  KOH  -  . 

DIFF.     Col.     Chem.  6. 

NOTE.     Gives  off  arsenic  odor  when  ground  on  coarse  wheel. 

SMALTITE  CoAs2 

COL.     White.     With  galena,  pale  creamy  white;    with  arsenopyrite, 

white;   with  safflorite,  creamy  white. 

HARD.     High.  SURF.     Shiny  but  pitted.  H.  5.5-6  =  Py. 

CHEM.     1.   HNOs.     Instantly  blackens  with  effervescence.     Rubs  to 

persistent  gray.     2.  KCN—-.      3.  HC1  -  .     4.  HC1  cone.  -  .     5. 

Aq.  Reg.    Effervescence  begins  very  slowly  and  increases  in  rapidity. 

Then  mineral  begins  to  turn  brown  rather  quickly  and  develops 

structure.     Rubs  off  to  show  roughened  gray  surface,  with  structure 

well  brought  out.     6.  FeCls.    Rapidly  blackens,  and  shows  etched 

surface.     7.  KOH  -  .     8.  NH4OH  -  . 
DIFF.     Col.     Chem.  6. 

NOTE.     Gives  off  arsenic  odor  when  ground  on  coarse  wheel. 

SKUTTERUDITE  ?  CoAs3 

COL.     White.     With  smaltite,  practically  the  same  (creamier?). 
HARD.     High.  SURF.     Shiny,  pitted.  H.  =  6 

CHEM.  1.  HNOs.  Quickly  blackens  with  effervescence,  showing  a 
white  coating.  Zonal  structure  developed  by  differential  etching. 
Rubs  to  very  rough  surface.  2.  KCN  -  .  3.  HC1  -  .  4.  Aq.  Reg. 
Effervesces  quickly  at  first,  then  slowly  and  again  increases. 
Slowly  turns  brown.  Etched  differentially.  Rubs  clean.  5.  FeCls. 
Quickly  brown,  differentially,  one  part  practically  untouched.  6. 
KOH  -  . 
DIFF.  Col.  Chem.  1. 

NOTE.     May  be  smaltite,  or  smaltite  may  be  skutterudite.     Gives 
off  arsenic  odor  when  ground  on  coarse  wheel.    , 

MAUCHERITE         See  page  79. 


r 

2 


03 


tr 


83 


WHITE 

HARDNESS  HIGH 
No  EFF.  HNOs 
HC1  UNCHANGED 
Err.  AQ.  REG. 


I 


FeCls  Neg. 


LOLLINGITE  FeAsi 

COL.  White.  With  galena,  very  faint  creamy  white;  with  silver, 
practically  pure  white  with  a  suggestion  of  pink;  with  arsenopyrite, 
same  as  with  silver. 

HARD.     High.  SURF.     Shiny  but  pitted.  H.  5-5.5  =  py. 

CHEM.  1.  HNOs.  Very  faintly  brown,  especially  by  fumes.  2.  KCN 
-  .  3.  HC1  -  .  4.  HC1  cone.  -  .  5.  Aq.  Reg.  Slowly  effervesces 
and  very  slowly  turns  faint  brown,  easily  rubbed  clean.  6.  FeCls  -  . 
7.  KOH  -  .  8.  NaOH  -  .  9.  (NH4)2S*.  Slowly  brown,  dries 
iridescent  brown;  rubs  clean  easily.  10.  NH4OH  -  . 

DIFF.     Chem.  I,  6. 

NOTE.     Gives  off  arsenic  smell  when  ground  on  coarse  wheel. 


ULLMANITE  NiSbS 

COL.  White.  With  galena,  white  with  very  faint  creamy  tint;  with 
arsenopyrite,  practically  pure  white. 

HARD.     High.  SURF.     Shiny  but  pitted.  H.  5.^6. 

CHEM.  1.  HNOs.  Tarnishes  quickly  brown,  then  bright,  repeating 
with  higher  order  colors;  rubs  to  persistent  iridescent  gray.  2.  KCN 
-  .  3.  HC1  -  .  4.  HC1  cone.  -  .  5.  Aq.  Reg.  Effervesces  strongly 
and  blackens  rapidly,  effervescence  stopping  when  black  film  forms. 
Rubs  to  persistent  dull  gray.  6.  FeCls  -  .  7.  KOH  -  .  8. 
NH4OH  -  . 

DIFF.     Chem,  1,  6. 


ARSENOPYRITE     See  page  82. 


i  » 


84 


E 
O 

X 
M 

1 

4       c* 

c         < 

CHLOANTHITE                                   NiAs,  jj               C 

COL.     White.     With  arsenopyrite,  pure  white;   with  galena,  faintly  0 

creamy  white;  with  silver,  pure  white;  with  rammelsbergite,  same  £ 

color.  >-> 

HARD.     High.             SURF.     Shiny  but  pitted.                         H.  5.5-6.  ^ 

CHEM.     1.  HNOs.    Rather  quickly  brown,  with  tarnish  around  edges  of  _H 

drop;  rubs  to  brownish  gray,  roughened  surface.     2.  KCN .      3.  O 

HC1  cone. .     4.  Aq.  Reg.    Effervesces  and  slowly  darkens.    Rubs  ^ 

faint.     5.  FeCls.    Mineral  practically  unchanged,  but  solution  turns  K 

dark  yellowish  brown.     6.  KOH .  s_ 

DIFF.     Chem.  4,  5. 

NOTE.     Gives  off  arsenic  odor  when  ground  on  coarse  wheel. 

RAMMELSBERGITE  NiAs,  S 

COL.     White.     With  galena,  pale  creamy  white;   with  silver,  practi-  £•< 

cally  pure  white;  with  chlpanthite,  same;  with  arsenopyrite,  white. 

HARD.     High.       SURF.     Shiny  but  often  pitted.  H.  5.5-6.  !^ 

CHEM.     1.  HNOs.     Rather  quickly  brown,  with  tarnish  around  the  UJ 

edges.      Shows   a   roughened    surface.      2.   KCN .      3.   HC1 .  Jg 

4.  HC1  cone. .     5.  Aq.  Reg.     Effervesces  slowly  and  solution  turns 

greenish  yellow;  shows  roughened  surface.     6.  FeCla.     Very  slowly  fa 

faint  brown,  persistent.     7.  KOH . 

DIFF.     Chem.  5,  6. 

NOTE,     Gives  off  arsenic  odor  when  ground  on  coarse  wheel.  ^ 

O 

| 


i  * 

":  i 

£  CA 

3  CA 

£  W 

Q  Q 

8  Sj 

85  E 


WHITE 

HARDNESS  HIGH 
No  EFF.  HNOj 
HC1  UNCHANGED 
No  EFF.  AQ.  REG. 


Aq.  Reg.  Neg. 


I 


COBALTITE  CoAsS 

COL.  White.  With  galena,  pale  creamy  brown;  with  silver,  same  as 
with  galena;  with  arsenopyrite,  pale  pinkish  brown. 

HARD.     High.  SURF.     Scratched  and  dull.  H.  5.5-6  =  py. 

CHEM.  1.  HNOs.  Very  faintly  browned,  shows  only  after  rubbing.  2. 

HC1 .  3.  HC1  cone. .  4.  KCN.  Slowly  very  pale  brown,  rubs 

clean.  5.Aq.Reg. .  6.FeCl3 .  7.KOH .  8.HN4OH . 

DIFF.     Col.     Chem.  5. 


LINN  JEITE        See  page  79. 


I 


I 


I 
I 


I 


86 


£ 

O 

53 


Aq.  Reg. 


GLAUCODOT  (CoFe)AsS 

COL.  White.  With  galena,  pale  (brownish)  creamy  white;  with 
silver,  very  pale  brownish  white;  with  arsenopyrite,  very  pale  pink- 
ish white.  (Observed  on  a  crystal  face,  not  an  artificially  polished 
surface.) 

HARD.     High.  SURF.     Scratched  and  dull.  H.  5. 

CHEM.     1.  HNOs.     Readily  turns  dark  gray,  producing  rough  surface. 

2.  KCN .     3.  HC1 .     4.  HC1  cone. .     5.  Aq.  Reg.  Very 

slowly  tarnished  dark  brownish  gray,  persistent.     6.  FeCls .     7. 

KOH .     8.  Ammonium  molybdate,  10  per  cent . 

DIFF.     Col.     Chem.  1,  5. 

NOTE.    Gives  off  arsenic  odor  when  ground  on  coarse  wheel. 


PENTLANDITE         See  page  100. 


i 

I 

U 

E 


u: 

Q 


§ 

a 

LU 

S 

ca 

I 

a 


87 


s 

ca 
ca 

UJ 

Z 

Q 
U 
< 
E 


V 

WHITE 

HARDNESS  HIGH 

No  EFF.  HNO3 

HC1  TURNS  YELLOWISH  GREEN 


GERSDORFFITE  NiAsS 

COL.  White.  With  galena,  faintly  brownish  creamy  white;  with 
arsenopyrite,  practically  pure  white. 

HARD.     High.  SURF.     Shiny,  but  rough.  H.  5.5. 

CHEM.  1.  HNOs.  Immediately  tarnishes  bright,  then  in  a  few  seconds 

blackens;  rubs  to  gray  roughened  surface.  2.  KCN .  3.  HC1 

acid  turns  bright  yellowish  green.  4.  HC1  cone.  Same  as  HC1. 
5.  Aq.  Reg.  Very  slowly  tarnishes  brown,  sometimes  with  efferves- 
cence; persistent.  6.  FeCls .  7.  KOH .  8.  NH^OH .  9. 

Picric  acid  10  per  cent . 

DIFF.     Chem.  1,  5. 


I 

I 
I 


I 
I 


I 

Cfl 

I 

0 


5 

OJ 


UJ 

a 

^ 

E 


i! 


S 


H 

s 


LU 

z 

a 
c* 


WHITE 

HARDNESS  HIGH 
HNO3  NEG. 


HC1  Cone.  Neg. 

I" 

!  RUTILE  TiOa 


COL.  White.  With  galena,  pale  grayish  white;  with  tetrahedrite, 
very  slightly  grayer.  Sometimes  shows  transparent  red  with  oblique 
light,  and  is  then  bluer  by  vertical  illumination. 

HARD.     High.  SURF.     Shiny,  pitted.  H.  6-6.5. 

CHEM.     Not  attacked  by  any  reagents. 

DIFF.     Chem.     Col. 

NOTE.     Very  hard  to  polish  free  from  pits. 


ILMENITE  FeTiOi 

COL.     White.     With  galena,  pale  grayish  white;  with  sphalerite,  dis- 

tinctly  whiter;     with   magnetite,    pale   purplish;     with   hematite, 

distinct  pale  purplish  gray;  with  tetrahedrite,  slightly  grayer. 

HARD.     High.  SURF.     Shiny,  pitted.       H.  4.5-5  >  magnetite. 

CHEM.     1.  HNO3  -  .     2.  KCN  -  .      3.  HC1  cone.  -  .     4.  HC1  cone. 

hot  -  .     5.  Aq.  Reg.  -  . 
DIFF.     Col.     Chem. 

NOTE.     Very  hard  to  polish  free  from  pits.     Sometimes  shows 
slight  variation  in  color.    Frequently  intergrown  with  magnetite. 


HEMATITE  Fe2O3 

COL.     White.     With  galena,  pale  creamy  grayish  white;  with  magne- 

tite,  white;  with  tetrahedrite,  lighter,  bluish?  white. 
Occ.     Often  as  plates  (specularite)  ,  and  then  easily  recognized  by  form 

and  hardness  alone.    Sometimes  massive,  intergrown  with  magnetite. 
HARD.     High.  SURF.     Shiny,  pitted.  H.  5.5-6.5  =  mg. 

CHEM.     1.  HNOs  -  .     2.  KCN  -  .     3.  HC1  -  .      4.  HC1  cone.  -  . 

5.  Aq.  Reg.  -  .     6.  FeCl3  -  .     7.  KOH  -  .     8.  HC1  cone,  hot  -  . 

9.  HNO3  hot  -  . 
DIFF.     Col.    Occ.     Chem.     Hard. 

NOTE.    Very  hard  to  polish  free  from  pits. 


PYRRHOTITE         See  page  76. 
FRANKLINITE         See  page  144. 


I 
I 


90 


HC1  Cone. 


MAGNETITE  Fe3O4 

COL.     White.     With  galena,  very  dull  (purplish)  grayish  white;  with 

sphalerite,  distinctly  lighter,  with  suggestion  of  creamy;  with  hema- 
tite, faint  creamy  brown;   with  ilmenite,  lighter  and  creamy;   with 

tetrahedrite,  very  pale  grayish  brown.     Sometimes  has  a  purnlish 

tarnish,  persistent. 

HARD.  High.  SURF.  Shiny,  pitted.  H.  5.5-6.5  <  ilmenite  and  hematite. 
CHEM.     1.  HNO3  cone. .     2.  KCN .     3.  HC1  cone,  slowly  turna 

brown,  some  grains  faster  than  others.     Acid  turns  yellow.     4  Aq. 

Ref-     Same  as  HclcoQc.      5.  HC1  cone.  hot.     Readily  blackened 

and  dissolved. 
DIFF.     Col.     Chem.  5. 

NOTE.     Very  hard  to  polish  free  from  pits. 

SPERRYLITE  PtAs2  Jg 

C°L.     White  (not  compared  with  any  mineral,  but  appears  white). 

1  he  specimens  examined  were  not  polished,  but  were  minute  crys-  M 

tals,  mounted  in  sealing  wax,  and  the  reactions  observed  on  the  O 

crystal  faces.  » 

CHEM.     1.    HNO3 .     2.    KCN .     3.    HC1 .^t^Hd    cone*  5? 

Very  slowly  faint  yellow,  washes  off,  leaving  surface  unchanged. 

Yellow  probably  due  to  coloration  of  acid.     Test  doubtful.     5.  Aq.  t/\ 

Keg.    bame  as  HC1  cone,  but  slower.    6.  FeCls .     7.  KOH .     8  JJ? 

KClOs  and  H2SO4  cone.    Quickly  bright  orange  yellow,  then  darker'  % i 

to  bright  yellowish  brown.     Washes  off  to  very  pale  brown,  which  fes 

rubs  off  easily.     9.H2SO4conc.    Slowly  light  brownish  yellow,  deep-  Z 

enmg  gradually,  easily  washes  off  clean.     Like  KC1O3  and  H2SO<  O 

cone,  but  less  vigorous.  *-* 

DITF.     Chem.  8,  9.  UZ 


UNKNOWN  PINKISH  MINERAL  (in  Mohawkite)         See  page  76. 


91 


WHITE 

HARDNESS  MEDIUM 
GRAYISH  WHITE 
HNOs  NEQ. 


KCN  Neg. 


BOURNONITE  (PbCu2)3Sb2S6 

COL.     White.      With  galena,  very  pale  grayish  white,  very  nearly 
same;    with  silver,  dull  grayish  (bluish)  white;    with  tetrahedrite, 
grayish  white,  no  brown. 
HARD.     Medium  or  low.  SURF.     Smooth.  H.  2.5-3  <  td. 

CHEM.     1.  HNO3 .     2.  KCN .     3.  HC1 .      4.  HC1  cone. . 

5.  Aq.  Reg.    Quickly  blackens  with  effervescence,  produces  a  coating 

of  free  sulphur.     6.  FeCls .     7.  KOH .     8.  NH4OH . 

DIFF.     Chem.  2,  5. 

NOTE.  Some  bournonite  is  turned  brown  by  HNOa,  acid  and 
fumes,  or  by  acid  alone.  Brighter  along  cracks  in  the  mineral, 
or  around  pyrite  grains. 


TENORITE  CuO 

COL.  White.  With  galena,  pale  greenish  gray,  and  darker  greenish 
gray  (hard  and  soft  portions);  with  tetrahedrite,  hard  part  nearly 
the  same,  and  soft  decidedly  darker.  The  soft  part  is  probably  the 
earthy  form,  melaconite. 

Occ.  Often  crusted,  like  some  limonite,  with  layers  of  varying  hard- 
ness; or  in  minute  plates  or  crystals. 

HARD.     Medium.  SURF.     Smooth.  H.  3-4. 

CHEM.  1.  HNO3 .  2.  KCN .  3.  HC1.  Quickly  darkens;  drop 

spreads  out  rapidly,  forming  and  carrying  with  it  a  ring  of  pale  green- 
ish blue  coating.  Then  acid  rapidly  evaporates,  leaving  a  mass  of 
minute  acicular,  nearly  colorless  crystals  on  the  surface.  Fumes 
tarnish  brilliant  iridescent.  Fumes  and  coating  wash  off  readily. 
4.  Aq.  Reg.  Same  as  HC1.  5.  FeCls.  Very  slowly  faint  brown,  rubs 
clean  easily.  6.  KOH . 

DIFF.     Chem.  3. 


DELAFOSSITE  Cu,  Fe,  O 

COL.  Pale  creamy  gray.  With  galena,  creamy  gray;  with  sphalerite, 
grayish  cream;  with  tetrahedrite,  slightly  yellower  and  duller. 

HARD.     Medium.  SURF.     Smooth.  H.  2.5  >  copper. 

CHEM.  1.  HNOs .  2.  KCN .  3.  HC1.  Darkens  slightly  and 

rather  rapidly  dissolves,  developing  structure.  Shows  etched  sur- 
face clearly  after  rubbing.  4.  Aq.  Reg.  Etches  rather  slowly  and 

slightly.  Acid  quickly  turns  yellowish  green.  5.  FeCls .  6. 

KOH . 

DIFF.     Col.     Chem.  3. 


TETRAHEDRITE        See  page  94. 
R  REGNOLITE         See  page  104. 


1 


KCN 

0 

z 

8 

POLYBASITE         See  page  105. 
ENARGITE         See  page  95. 
ARGYRODITE         See  page  105. 


5 

6  gj 

2  S 

C  W 

8  S3 

S  z 

3  O 

I*  or 


6 

z 

E 


WHITE 

HARDNESS  MEDIUM 
GRAYISH  WHITE 
FUMES  HNO3 


KCN  Neg. 


TETRAHEDRITE  Cu8Sb2S7 

COL.     Grayish  white.     With  galena,  dull  pale  gray  with  a  suggestion 

of  brown.     Slightly  variable,  grading  towards  tennantite  in  color. 
HARD.     Medium.  SURF.     Smooth.  H.  3-4.5  =  cp. 

CHEM.    1.  HNOa .    Fumes  tarnish  slowly  light  brown,  rubs  off  easily 

(sometimes  not  affected  even  by  fumes).      2.  KCN (see  note). 

3.  HC1 .     4.  HC1    cone. .      5.  Aq.  Reg.      Slowly  effervesces, 

acid  turns  greenish  yellow;  after  a  few  minutes  shows  a  coating  of 
sulphur,  which    can  be  rubbed  off,  leaving  a  pitted  surface.      6. 

FeCls .      7.  KOH .      8.  (NH4)2SX.     Slowly    tarnished    bright 

brown,  rubs  off.     9.  K4Fe(CN)6 .     10.  K3Fe(CN)6 . 

DIFF.     Col.     Chem.  1,  5  (grades  towards  tennantite  in  properties). 
NOTE.     Freibergite,  the  silver  bearing  tetrahedrite,  is  very  close 

to  this,  but  is  tarnished  bright  iridescent  with  HNOs. 
Mercurial  tetrahedrite  is  slightly  bluer,  and  is  slowly  tarnished 
bright  iridescent  with  HNOs.     KCN  left  on  for  about  a  minute 
and  a  half  turns  ordinary  tetrahedrite  very  faint  brown,  and 
etches  it  slightly. 
Gives  a  reddish  streak  on  the  canvas  wheel. 


TENNANTITE  Cu8As2S7 

COL.     Grayish  white.     With  galena,  dull  grayish,  with  a  suggestion  of 
green;    with  tetrahedrite,  slightly  bluer  gray,  grading  towards  the 
same  color. 
HARD.     Medium.  SURF.     Smooth.  H.  3-4.5  =  cp. 

CHEM.    1.  HNOs .    Fumes  tarnish  bright  brown,  rubs  off.     2.  KCN 

(see  note).    3.  HC1 .     4.  HC1  cone.  .     5.  Aq.  Reg.    Slowly 

effervesces,  tarnishes  bright  iridescent  in  a  few  moments.     Rubs  off 

to  show  a  pitted  surface.     6.  FeCla .     7.    KOH .     8.  (NH4)2SX. 

Rather  quickly   bright    brown.     9.    K3Fe(CN)6.     Slowly  tarnished 

brown,  rubs  off.     10.  K4Fe(CN)6 .     11.  Iodine . 

DIFF.     Col.     Chem.  1,  5  (grades  towards  tetrahedrite  in  properties). 
NOTE.     With  KCN  for  1^  minutes  acts  same   as   tetrahedrite. 
Gives  a  reddish  streak  on  the  canvas  wheel. 


HAUERITE  MnS2 

COL.     Grayish  white.     With  galena,  pale  gray  or  grayish  white;  with 

tetrahedrite,  slightly  white,  or  more  neutral,    with  no  yellowish 

tinge.     Practically  opaque. 

HARD.     Medium.               SURF.     Smooth.                                     H.  =  4. 
CHEM.    1.  HNO3 .    Fumes  tarnish  a  little,  very  slowly.    2.  KCN . 

3.  HC1 .     4.  Aq.  Reg.     Slowly  very  faint  brown.     Fumes  tarnish 

faintly.     Rubs  clean  easily,  leaving  a  smooth  surface.     5.  FeCla . 

6.  KOH . 

DIFF.     Chem.  4. 

NOTE.     Gives  an  orange  streak  on  the  canvas  wheel. 


BOURNONITE         See  page  92. 


l 


KCN 


ENARGITE 

COL.     White.     With  galena,  very  dull  grayish  white,  with  a  suggestion 
of  pinkish  brown;   with  silver,  very  dull  grayish  white;   with  argen- 
tite,  dull  pinkish  gray;   with  tetrahedrite,  decidedly  pinkish  gray. 
HARD.     Medium.  SURF.     Smooth.  H.  3  =  cp. 

CHEM.    1.   HNOs .    Fumes  slowly  tarnish  faint  brown.    2.   KCN. 

Quickly  blackens  and  etches.     Rubs  clean,  showing  etched  surface 

with  structure  or  cleavage  developed.     3.  HC1 .     4.  HC1  cone. . 

5.  Aq.  Reg.    Quickly  brown,  appears  to  roughen ;   rubs  clean  easily. 

Fumes  tarnish  slightly.    6.   FeCl3 .     7.   KOH .     8.    (NH4)2SX- 

Slowly  bright  brown,  iridescent;  rubs  clean  easily.      9.  KiFe(CN). 

.     10.  K4Fe(CN)6 .     11.  Iodine . 

DIFF.     Chem.  2,  5. 

NOTE.  Ordinary  enargite,  faintly  pinkish,  is  here  called  white 
enargite.  This  shows  perfect  cleavage,  and  may  be  wholly  pure 
Cu;iAsS4,  or,  as  in  some  cases,  may  carry  considerable  antimony 
without  appreciably  altering  its  physical  or  microchemical 

properties.     (Some  antimonial  enargite  from  Peru,  however,  is  JJ 

browned  and  etched  by  HNOa,  while  ordinary  enargite  is  not.) 

Massive  white  enargite,   without   cleavage,    but  in   crystal  ~  ^ 

grains,  as  shown  by  etching,  has  been  observed  from  Goldfield.  Q  UJ 

This  carries  equal  portions  of  antimony  and  arsenic.  ^  5 

Pink  enargite,  which  shows  decidedly  pink  against  ordinary  X-i 

enargite,  has  not  been  observed  in  crystals,  except  granular  T  t\ 

aggregates,  without  good  crystal  form,  and  never  shows  cleav- 
age.  It  carries  apparently  all  proportions  between  practically 
all  arsenic  and  no  antimony,  to  nearly  all  antimony  and  no 
arsenic.  The  former  corresponds  to  luzonite,  and  the  latter  to 
famatinite.  An  intermediate  member  occurs  in  Goldfield,  with 
about  equal  amounts  of  antimony  and  arsenic.  This  has 
slightly  different  microchemical  properties  from  other  pink 
enargites. 

A  whiter  form  of  famatinite,  with  cleavage,  that  is,  the  anti- 
mony  end-member  of  the  normal  enargite  series,  has  not  yet 
been  observed. 

Enargite  is  frequently  intergrown  curiously  with  tennantite, 
giving  the  former  a  mottled  appearance.  This  is  very  common 
at  Butte,  and  has  been  called  "mottled  enargite"  by  L.  C. 
Graton  and  the  writer.  The  enargite  in  this  intergrowth  is  free 
from  antimony,  and  also  varies  perceptibly  in  degree  of  pinkness. 


o        « 

Z  c/) 

8          m 

Q 


95 


fi 


i 


WHITE 

HARDNESS  MEDIUM 
GRAYISH  WHITE 
HN03 


KCN  Neg. 


ALGODONITE  (GRAY)  Cu«As? 

COL.  Grayish  white  (part  of  a  mixture).  With  galena,  very  pale 
gray. 

HARD.     Medium.  SURF.     Smooth.  H.  4? 

CHEM.  1.  HNOs.  Instantly  blackens,  with  effervescence,  leaving  a 

rough  surface.  2.  KCN .  3.  HC1 .  4.  Aq.  Reg. .  5. 

FeCl3 .  6.  KOH.  Turns  yellowish  brown.  7.  (NHOzSx.  In- 
stantly bright  iridescent.  8.  Iodine .  9.  K4Fe(CN)6.  Blackened, 

rubs  clean.  10.  KsFe(CN)G.  Faint  brown,  rubs  clean. 

DIFF.     Chem.  I,  4. 


POLYTELITE  4(PbAgFeZn)S-Sb2S3? 

COL.     White.     With  galena,  dull  grayish  white;    with  tetrahedrite, 

slightly  grayer? 

HARD.     Medium.                SURF.     Smooth.                              H.?  =  Td? 
CHEM.    1.  HNOs.    Slowly  bright  brown  and  iridescent,  persistent.    2. 
KCN .     3.  HC1 .     4.  Aq.  Reg.    Instantly  bright  brown,  effer- 
vesces and  blackens,  persistent.     5.  FeCls .     6.  KOH . 

DIFF.     Chem.  1,  2. 

NOTE.     Distinguished  from  freibergite  only  by  the  absence  of 
copper.     This  is  a  very  doubtful  species. 


ALABANDITE  MnS 

COL.  Grayish  white.  With  galena  very  pale  dull  gray;  with  silver, 
pale  bluish  gray;  with  argentite,  slightly  darker.  Transparent  green 
by  oblique  light. 

HARD.     Medium.  SURF.     Smooth.  H.  3.5-4  =  cp. 

CHEM.  1.  HNOs.  Instantly  effervesces  and  darkens;  rubs  to  light  gray 
with  little  solution  pits.  If  patch  is  large  enough,  odor  of  HsS  is 

evident.  2.  HNO3  cone.  Same.  3.  KCN .  4.  HC1.  Same  as 

HNO3.  5.  HC1  cone.  Same.  6.  Aq.  Reg.  Dissolves  readily  with 

evolution  of  H2S.  Leaves  a  rather  smooth  solution  pit.  7.  FeCls . 

8.  KOH .  9.  NaOH .  10.  Iodine.  Brilliant  tarnish;  rubs 

off  rather  easily  to  faint.  11.  (NH^Sx.  Very  slowly  iridescent; 

rubs  clean  easily.  12.  NH4OH .  13.  K3Fe(CN)6.  Slowly  faint 

brown;  rubs  off  easily.  14.  K4Fe(CN)e.  Same. 

DIFF.     Col     Chem.  1,  6. 


GEOCRONITE         See  page  132. 

FREIBERGITE         See  page  94  (note  under  tetrahedrite). 

BAUMHAUERITE         See  page  108. 

MOHAWKITE  (GRAY)         See  page  97. 

CROOKESITE         See  page  109. 

PLAGIONITE         See  page  135. 

STYLOTYPITE         See  page  97. 

BOURNONITE        See  page  92. 


[2 

^  96 


KCN 


UNKNOWN  MINERAL    (QuATisH  WHITE,  Butte,  N.  13) 

COL.     White.     With  galena,  faint  brownish  grayish  white;  with  silver, 

decidedly  grayish  white;    with  tetrahedrite,  about  same,  but  less 

yellowish,  or  brown  (?). 

HARD.     Medium  to  low.       SURF.     Smooth.       H.  >  bn  <  unknown 

creamy,  Butte,  N  13. 
CHEM.     1.  HNOs.     Instantly  effervesces  and  turns  gray,  persistent. 

Develops  cracks,  rubs  off  rough.    2.  KCN.    Instantly  brilliant  iri- 
descent.    Rubs  easily  to  pale,  persistent  tarnish.     3.  HC1 .     4. 

Aq.    Reg.     Quickly  darkens  and  roughens.     Rubs  fairly  easily  to 

original  color.     5.  FeCl3.     Rather  quickly  darkens,  finally  grayish 

brown;   develops  cracks;   rubs  off  easily.     6.  KOH . 

DIFF.     Chem.  1,  2. 

NOTE.     Probably  carries  Bi. 

MOHAWKITE  (GRAY)  Cu3As  (with  Ni  and  Co)?  — 

COL.     Grayish  white.     With  galena,  very  pale   (yellowish  ?)   gray; 

with  silver,  same  'as  with  galena.     Has  needles  of  purplish  color  in  it,  *D 

like  those  in  domeykite.  ** 

HARD.     Medium.  SURF.     Smooth.  H.  4.  Q 

CHEM.    1.  HNO3.    Effervesces  violently,  turns  purple,  then  black.    2. 

KCN ?  (with  unknown  pinkish  mineral,  is  slowly  etched).     3.  M 

HC1 (with  unknown  pinkish  mineral  is  etched).     4.  Aq.  Reg. ^ 

(with  unknown  pinkish  mineral,  is  etched).     5.  FeCls .     6.  KOH. 

Tarnishes  bluish,  rubs  off,  leaving  purplish  tinge.     7.  NaOH.     Tar-  W) 

nishes  brown,  then  brilliant,  persistent.    8.  NH4OH.  Blackens,  then  (/) 

turns     iridescent.         9.     (NH^Sx.       Instantly     iridescent.       10.  [Tj 

K3Fe(CN)6.     Slowly  brilliant  colors,  very  persistent.      Forms  solu-  5 

tion  pit.  £-* 

DIFF.     Occurrence  as  part  of  intergrowth.     Chem.  6.  Q 

* 

STYLOTYPITE  (Cu2Ag2Fe)3  Sb2Se? 

COL.     White.     With  galena,  grayish  white;    with  tetrahedrite,  prac- 
tically the  same. 

HARD.     Medium.  SURF.     Smooth.  H.  3  =  cp. 

CHEM.    1.  HNO3.    Very  slowly  brownish  yellow  and  red.    Some  grains 

hardly  touched.     Fumes  tarnish  slightly.     Rubs  clean  easily.     2. 

KCN.     Turns  faint   gray?     Rubs  clean  easily,   leaving  a  slightly 

roughened  surface.     (Test  is  not  well  established.)     3.  HC1 .     4. 

Aq.  Reg.     Slowly  pale  brown.     After  a  while  effervesces  slightly. 

Fumes  tarnish  a  little.     Rubs  clean  easily.     5.  FeCls .     6.  KOH. 

Very  slowly  faint  brown.     Rubs  easily  to  very  faint  brown,  slightly 

roughened  surface. 
DIFF.     Chem.  1. 


PLAGIONITE         See  page  135. 


0 

z 

E 


97 


WHITE 

HARDNESS  MEDIUM 

PINKISH  WHITE 


HNO3  Neg. 


LUZONITE 

COL.     Pink.     With  galena  and  silver,  pale  pink;   with  enargite,  dis- 
tinctly pale  pink.     Color  variable  faint  to  decided  pink. 

HARD.     Medium.  SURF.     Smooth.  H.  3.5  =  en. 

CHEM.     1.  HNO3 .      Fumes    tarnish    slightly.     2.  KCN.      Slowly 

darkens  and  dissolves,  like  enargite,  the  darker  pink  more  quickly 

than  the  paler.     3.  HC1 .     4.  Aq.  Reg.     Quickly  bright  iridescent, 

rubs  off  easily.     5.  FeCls .     6.  KOH . 

DIFF.     Col.     Chem.  2. 

See  note  under  enargite,  page  95. 


ENARGITE        See  page  95. 


is 
1 

s 


RA 


HNOt 


FAMATINITE 

COL.     White.     With  galena,  decidedly  pinkish  white;   with  enargite, 

distinctly  pinkish  white;   with  luzonite,  about  the  same. 
HARD.     Medium.  SURF.     Smooth.  H.  3.5. 

CHEM.     1.  HNOs.     Very  slowly  etched,  turning  brown,  some  parts 

more  rapidly  than  others;  at  last  iridescent.     Fumes  tarnish  faintly. 

Rather  persistent,  shows  etched  surface.      2.  KCN.     Rather  quickly 

brown,  then  iridescent,  slowly,  and  is  etched.     Rubs  to  grayish 

brown,  etched  surface.     3.  HC1 .     4.  Aq.  Reg.     Rather  quickly 

brown,    slight   effervescence.     Fumes   tarnish.     Rubs   clean   quite 

easily.     5.  FeCls .     6.  KOH . 

DIFF.     Col.     Chem.  1,  2. 

NOTE.  See  note  under  enargite,  page  95.  A  pink  mineral  from 
Goldfield,  carrying  equal  parts  of  As  and  Sb,  with  the  com- 
position of  an  enargite,  shows  the  following  behavior:  1.  HNOa 

.     Fumes   tarnish  faintly.     2.    KCN.     Very  quickly  dark 

brown,  then  black.     Etches  deeply. 

3 

OJ 

ARGYROPYRITE        See  page  101.  Jg 

Cft 
GEOCRONITE        See  page  132.  Cfl 

z 

BREITHAUPTITE        See  page  66.  Q 

Qtf 


V) 
CO 

UJ 

Q 
tt 


99 


WHITE 

HAKDNESS  MEDIUM 

CHEAMY  WHITE 


No  Eff.  HNO8 


PENTLANDITE  (FeNi)S 

COL.     Creamy  white.     With  galena,  very  pale  (creamy)  yellow,  not 

brown;   with  silver,  about  the  same  as  with  galena. 
HARD.     Medium.  SURF.     Shiny.  H.  3.5-4  <  po  >  cp. 

CHEM.     1.  HNOa.     Slowly  light  yellowish  brown  tarnish ;  rubs  off .     2. 

HNOs  cone.     Slowly  tarnishes  bright  yellow;   rubs  clean  easily.     3. 

KCN .      4.  HC1  cone. .      5.  Aq.  Reg.     Quickly  bright  brown, 

fumes  slightly  brown ;  rubs  clean  easily.      6.  FeCls .     7.  KOH . 

S.NaOH .    9.  (NH4)2SX .     10.  H2SO4  cone. .     ll.K3Fe(CN)6 

.     12.  K4Fe(CN)6 .     13.  Iodine . 

DIFF.     Chem.  1,  2. 


SULVANITE         See  page  72. 
CHALMERSITE         See  page  72. 
BRONZE  ENARGITE  See  page  74. 

BERTHIERITE         See  page  103. 
LINNJEITE         See  page  79. 
HAUCHECORNITE        See  page  79. 


100 


RA 


Eff.  HNOs 

i 

ARGYROPYRITE  Ag,  Fe,  S  and  As  ? 

COL.     White.     With  galena,  pale  creamy  white;  with  silver,  same  as 

silver. 

HARD.  Medium.    SURF.  Smooth  or  slightly  rough.    H.   3.5-4  >  arsenic. 
CHEM.     1.   HNOs.     Slowly  blackens,  with  effervescence;  rubs  off  to 

black  and  rough  surface.     2.  KCN .     3.  HC1 .     4.  AQ.  Ree. 

5.  FeCb .     6.  KOH . 

DIFF.     Chem.  1. 

NOTE.     Intermediate    between    argentopyrite  and  sterabergite, 
in  composition. 

AIKINITE  PbCuBiSa 

COL.     White.     With  galena,   pale   creamy;    with  silver,   very  pale 

grayish  white. 

HARD.     Medium  or  low.  SURF.     Smooth.  H  2-2.5.  >  bn. 

CHEM.     1.  HNO3.      Effervesces  and  blackens,  shows  whitish  coating 

(yellow  and  white  mixed)  on  surface  by  oblique  light.    Fumes  tarnish 

instantly  iridescent  then  blacken.     2.  KCN .    3.  HC1 .     4.  HC1 

cone.     Instantly  dark  brown,  persistent.     5.  Aq.  Reg.   Turns  brown  IT* 

with  slow  effervescence,  blackens.     Rubs  gray  and  rough.     Shows  UJ 

slight  white  coating.     Fumes  tarnish  instantly  bright  brown.     6. 

DIFF.     Col      Chem.  2.  y* 

CD 
ED 

DOMEYKITE         See  page  125.  ^ 

ALGODONITE  (CREAM)         See  page  74.  C 

MOHAWKITE  (CREAM)         See  page  74. 
WHITNEYITE         See  page  75. 
KALLILITE         See  page  82. 


3 

CD 

CD 

UJ 

Q 


a 

I 


WHITE 

HARDNESS  MEDIUM 

GALENA  WHITE 


S 


KOH  Neg. 


£ 
1 


1 


CHALCOSTIBITE  CttSbSa 

COL.     White.     With  galena,  very  pale  grayish  white. 

HARD.     Medium.  SURF.     Smooth.  H.  3-4. 

CHEM.  1.  HNO3 .  2.  KCN .  3.  HC1 .  4.  Aq.  Reg.  Fumes 

instantly  tarnish  narrow  rim  bright.  Acid  slowly  very  faint  brown- 
ish gray.  Rubs  clean  easily.  5.  FeCla .  6.  KOH . 

DIFF.     Chem.  6. 


BOURNONITE        See  page  92. 
POLYBASITE         See  page  105. 
GEOCRONITE         See  page  132. 
KALLILITE        See  page  82. 


H! 


S 

1 

I 
I 


102 


KOH 


BERTHIERITE  FeSb2S« 

COL.     White.     With  galena,  practically  the  same;  with  silver,  like 

galena. 

HARD.     Medium.  SURF.     Smooth.  H.  2-3. 

CHEM.     1.    HNOs  -  .     KCN  -  .     3.    HC1    cone.  -  .      4.    Aq.   Reg. 

Effervesces  and  turns  slowly  bright  yellowish  brown;  fumes  tarnish, 

rubs  clean  easily.     5.  FeCls  -  .      6.  KOH.     Slowly  bright  brown. 

7.     NaOH  Same  as  KOH,  but  more  quickly. 
DIFF.     Chem.  1,  6. 


GUEJARITE 

COL.     White.     With    galena,    nearly    the    same    (faintly    creamy). 

Shows  two  colors,  grayer  and  whiter  (probably  due  to  orientation). 

HARD.     Medium.  SURF.     Smooth.  ^, 

CHEM.     1.  HNOs.     Quickly  bright  iridescent,  then  blackens.     Rubs  2 

easily  to  gray,  roughened  surface.     2.  KCN.     Slowly  faint  brown. 

Rubs  clean  easily.     3.  HC1  -  .     4.  Aq.  Reg.    Slowly  bright  irides-  S< 

cent.     Slowly    efferyesces.     Rubs    clean    easily.     5.    FeCls  -  .     6. 

KOH.     Instantly  iridescent,  then  blackened  rapidly.     Coated  with 

yellow.     Rubs  off  clean  to  show  deeply  dissolved  and  roughened 

surface.  5? 

DIFF.     Chem.  6. 

NOTE.     Observations  were  made  on  minute  crystals  mounted  in  CO 

sealing  wax,  so  that  reactions  may  be  somewhat  affected.  (/) 

01 
O 


s 


EH 

z; 

Q 

e 


103 


WHITE 

HARDNESS  Low 
GRAYISH  WHITE 
HNO3  NEG. 


KCN  Neg. 


MOLYBDENITE  MoS2 

COL.  White.  With  galena,  mixture  of  dull  grayish  white  (with 
purple  tinge),  and  white;  with  silver,  mixture  of  dull  purplish  gray 
and  white.  Different  colors  due  to  different  orientation? 

HARD.     Low.  SURF.     Smooth.  H.  1-1.5  >  cc.? 

CHEM.  1.  HNO3 .  2.  KCN .  3.  HC1 .  4.  Aq.  Reg. .  5. 

FeCla .  6.  KOH .  7.  NH4OH . 

DIFF.     Col.     Chem.  1,  2,  4. 

REGNOLITE  Cu7As2Si2 

COL.     Grayish  white.     With  galena,  greenish  grayish  white;    with 

tetrahedrite,  pale  greenish. 

HARD.     Low.                       SURF.     Smooth.  H.  <  SI. 

CHEM.     1.     HNO3 .      2.     KCN .     3.     HC1 .     4.     Aq.     Reg. 

Rather  slowly  bright  brown.     Fumes  tarnish  faintly.     Rubs  clean 

easily.     5.  FeCls .     6.  KOH . 

DIFF.     Chem.  4. 

SELIGMANNITE  CuPbAsS3 

COL.     White.     With  galena,  grayish  white;    with  tetrahedrite,  very 

slightly  lighter. 

HARD.     Low.                      SURF.     Smooth.  H.  =  3. 

CHEM.     1.  HNOs .     2.  KCN .     3.  HC1 .     4.  Aq.  Reg.    Very 

quickly  blackens  with  effervescence.     Thinly  coated  with  white. 

Rubs   to   rough   gray   surface.     5.    FeCls .     6.    KOH.     Rather 

slowly  darkens  to  pale  bluish  iridescent.     Rubs  clean  easily. 
DIFF.     Chem.  6. 

NOTE.     Practically  the  same  as  rathite  in  chemical  properties. 

ARGENTIFEROUS  JAMESONITE  (near  Brogniardite) 

COL.     White.     With  galena,  pale  grayish  white. 

HARD.     Low.  SURF.     Smooth.  H.  <  cp. 

CHEM.     1.   HNOs .     Fumes  slowly  faint  brown.      2.   KCN ?    (or 

possibly  very  faint  gray).     3.  HC1 .     4.  Aq.  Reg.     Effervesces 

slightly,  and  turns  brown  and  iridescent.     Fumes  tarnish  instantly. 

Rubs  to  faint  gray,  roughened  surface.     5.  FeCls .     6.  KOH . 

DIFF.     Chem.  4. 

NOTE.  This  mineral  is  distinctly  browner  than  ordinary  jame- 
sonite,  and  does  not  agree  in  properties  with  any  other  mineral 
in  this  collection. 


CINNABAR         See  page  141. 

KALGOORLITE         See  page  124. 

BOURNONITE         See  page  92. 

TIEMANNITE         See  page  114. 

CQ  RATHITE         See  page  141. 

^  LENGENBACHITE         See  page  141. 

t  UNKNOWN  (Tonopah)         See  page  114. 

1 

U<  104 


KCN 


ORPIMENT  As2S3  £ 

COL.     White.     With  galena,  pale  grayish  white;  with  proustite,  pale  J? 

(purplish)  grayish  white;   with  tetrahedrite,  dull  bluish  gray;   with  O 

cuprite,  same  as  with  proustite?     Transparent  yellow  by  oblique  ^ 

light.  XH 

HARD.     Low.  SURF.     Smooth.  H.  1.5-2. 

CHEM.  1.  HNO3  -  .  2.  HNO3  cone.  -  .  3.  KCN.  Quickly  dark, 
persistent.  4.  HC1  cone.  -  .  5.  Aq.  Reg.  Fumes  darken?  6. 
FeCl3  -  .  7.  KOH.  Instantly  blackens  and  dissolves.  8.  (NH4)2SX. 
Dissolves  and  forms  rough  surface.  9.  K3Fe(CN)6  -  . 

DIFF.     Col.     Chem.  3,  4. 

ARGYRODITE  AgeGeSs 

COL.     White.     With  galena,  dull  grayish  white;    with  tetrahedrite, 

very  pale  bluish  gray,  no  brown. 

HARD.     Low.  SURF.     Smooth.  H.  2  5 

CHEM.     l.'-.HNOs  -  .     2.  KCN.     Rather  quickly  brown,  developing 

structure  by  differential  attack.     Rubs  easily  to  a  faintly  etched 

surface.    3.  HC1  -  .     4.  Aq.  Reg.    Instantly  iridescent;  rubs  bright 

iridescent,  persistent.     5.  FeCls  -  .     6.  KOH  -  . 
DIFF.     Chem.  2,  4,  5. 

POLYBASITE  Ag9SbS6 

COL.     White.     With  galena,  very  pale  grayish  (greenish)  white;  with 

silver,  bluish  grayish  white;  with  argentite,  practically  white;  with 

tetrahedrite,  grayish  white,  no  brown.     Color  is  slightly  variable. 
HARD.     Low.  SURF.     Smooth.  H.  2-3  =  gn 

CHEM.    1.  HNO3  -  .   2.  KCN.   Rather  quickly  dark  brown,  then  black  ; 

persistent,  shows  much  roughened  surface,  sometimes  with  structure 

developed.     3.  HC1  -  .     4.  HC1  cone.     Fumes  sometimes  blacken, 

but  this  varies  with  different  specimens,  and  some  polybasite  is  not 

affected  even  by  fumes.     5.  Aq.  Reg.     Iridescent,  with  very  slow 

effervescence,   and  not  much  tarnishing  by  fumes.     Rubs  clean, 

leaving  a  somewhat  roughened  surface,  usually.     6.  FeCl3  -  .     7. 

KOH  -  .     8.    (NH4)2SX.     Very  slowly   blackens,  partially?     This 

test  is  doubtful. 
DIFF.     Chem.  2,  5,  6. 

PEARCEITE  Ag9AsS,  0 

COL.     Grayish   (greenish)    white.     With  galena,   very  pale  grayish  Z 

green.  M 

HARD.     Low.  SURF.     Smooth.  H.  3  =  gn.  ** 

CHEM.    1.  HNO3  -  .  Fumes  tarnish;  tarnish  washes  off.  2.  KCN.  Very 

§uickly  blackens  and  dissolves.     Rubs  to  pale  gray,  rough  surface. 
•  H9ll"  —  '     4-  HC1  conc-  -  •     5-  M-  Reg.    Instantly  effervesces, 

turns  iridescent,  and  darkens  quickly.     Rubs  clean  very  easily.     6.  p^ 

FeCls.    Quickly  bright  iridescent.     Rubs  clean  easily.     7.  KOH  -  .  ^ 

DIFF.     Chem.  6.  Q 

JALPAITE         See  page  140.  ^ 

MIARGYRITE         See  page  115.  C/) 

STEPHANITE         See  page  142.  £J 
LIVINGSTONITE         See  page  142. 


105 


WHITB 

HARDNESS  Low 
GRAYISH  WHITE 
HNOs 
FeCls 


KCN  Weg. 


TEALLITE  PbSnSa 

COL.     White.     With  galena,  creamy  (?)  grayish  white;    with  tetra- 

hedrite,  slightly  lighter. 

HARD.     Low.  SURF.     Smooth.  H.  1-2. 

CHEM.     1.  HNOs.    Bright  brown,  then  brilliant  iridescent,  some  grains 

quickly,  some  more  slowly.     Rubs  clean  easily.     2.  KCN  -  .     3. 

HC1.     Slowly  yellowish  brown,  fumes  tarnish.     Rubs  clean  easily.    4. 

Aq.  Reg.     Instantly  iridescent,  with  effervescence;    darkens,  fumes 

tarnish.     Rubs  to  gray,  persistent.     5.  FeCls.    Slowly  faint  brown. 

6.  KOH.    Slowly  faint  brown. 
DIFF.     Chem.  1,  3. 


AGUILARITE  AgzS-AgzSe 

COL.     White.     With  galena,  pale  gray,  with  greenish  tinge  (?)  ;  with 

silver,  dull  pale  grayish  white. 

HARD.     Low.  SURF.     Smooth.  H.  2.5  <  cp. 

CHEM.    1.  HNO3.    Slowly  tarnished  brownish,  rubs  off  very  easily.    2. 

KCN  -  .     3.  HC1  -  .      4.  HC1  cone.  -  .     5.  Aq.  Reg.  -  ?     6. 

FeCls.    Slowly  bright  iridescent,  rubs  clean  easily.     7.  KOH  -  . 
DIFF.     Chem.  1,  3,  5. 


(PETZITE  ?  unknown)  ? 

COL.     White.     With  galena,  purplish  grayish  white;   with  silver,  de- 

cidedly purplish  grayish  white. 

HARD.    Low.  SURF.     Smooth.  H.  2.5-3  <  gold. 

CHEM.    1.  HNOs.    Instantly  blackens,  rubs  to  gray.    2.  KCN  -  .    3. 
HC1  -  .     4.  Aq.  Reg.     Instantly  bright  iridescent,  rubs  clean.     5. 
FeCh.     Instantly    iridescent;    fairly    persistent,  dries    bright.     6. 
KOH  -  . 
DIFF.     Chem.  1,  3,  4. 

NOTE.    Not  true  petzite,  and  usually  with  native  gold.    For 
petzite,  see  page  137. 


COLORADOITE  HgTe 

COL.  Grayish  white.  With  galena,  dull  pale  gray;  with  silver  and 
tetrahedrite,  same;  same  color  as  petzite  (?). 

HARD.     Low.  SURF.     Smooth.  H.  3. 

CHEM.  1.  HNOs.  Very  slowly  bright  brown,  then  brilliant  iridescent; 
rubs  clean.  2.  KCN  -  .  3.  HC1  -  .  4.  Aq.  Reg.  Slowly  bright 
iridescent,  with  effervescence;  rubs  clean  easily.  5.  FeCla.  Slowly 
faint  brownish.  Tarnished  at  edges  of  drop,  rubs  clean  easily.  6. 
KOH  -  . 

DIFF.     Chem.  1,3,4,  5. 


I 

fc 

g 
I 


106 


KCN 
CHALCOCITE  Cu2S 

COL.     Grayish  or  bluish  white.     Sometimes  "mottled,"  with  bright 
colors,  blue  or  green.     With  galena,  pale  bluish  or  grayish  white; 
with  silver,  pale  bluish  white;  with  cuprite,  slightly  whiter. 
HARD.     Low.  SURF.     Smooth.  H.  2.5-3  <  bn. 

CHEM.  1.  HNOs.  Effervesces  vigorously  and  etches,  turning  more  or 
less  blue.  Develops  cleavage  or  irregular  cracking.  2.  HNOa  cone. 
Effervesces,  turns  blue,  and  dissolves,  very  rapidly,  but  does  not 
develop  cleavage.  3.  KCN.  Very  rapidly  blackens,  rubs  off  to  show 
cleavage  or  cracking,  very  fine  graixied.  Dilute  KCN.  Produces 
coarser  etching.  4.  HCJi.  Change's  color  slightly  and  dissolves  a 
little.  5.  HC1  cone.  Same  as  HC1.  6.  Aq.  Reg.  Dissolves  readily, 
effervesces  and  develops  cleavage,  but  changes  color  only  slightly. 
7.  FeCls.  Dissolves  and  turns  slightly  paler  (?).  Does  not  develop 

structure.    8.     KOH .     9.     NaOH .     10.     NHiOH .     11. 

K3Fe(CN)6 .     12.  K4Fe(CN)8.     Slowly  faint  brown. 

DIFP.     Col.     Chem.  1. 

NOTE.  Color  variation  of  chalcocite  is  due  partly  to  admixture 
of  covellite  in  sub-microscopic  fragments  or  solid  solution.  The 
reds  and  greens  sometimes  observed  may  not  be  due  to  this. 
"Mottled"  chalcocite  of  this  sort  shows  true  chalcocite  cleav- 
age on  etching. 

e  CLEAVAGE.  The  writer  has  found  by  etching  oriented  sec- 
tions of  chalcocite  crystals  that  this  mineral  possesses  good 
cleavages  parallel  to  the  base  and  side  pinacoid,  and  a  poor  one 
parallel  to  the  front  pinacoid.  Therefore,  no  section  will  show 
more  than  two  good  cleavage  directions,  and  will  much  more 
often  show  one  good  cleavage  and  one  poor  one.  This  affords 
a  sure  distinction  between  chalcocite  which  has  its  own  crystal 
form,  and  chalcocite  derived  from  bornite,  which  retains  the 
structure  of  the  bornite.  In  this  case  any  section  will  show  at 
least  three  directions  of  cleavage,  of  equal  perfection  though  not 
necessarily  equally  abundant  in  development.  These  are  octa- 
hedral directions.  It  has  not  been  observed  in  unaltered  bornite, 
but  only  when  bornite  is  altering  to  chalcocite  apparently  under 
special  conditions. 

Anomalous  cleavages  have  been  noted  in  chalcocite  crystals 
from  certain  localities,  and  these  are  not  yet  fully  explained. 

When  in  too  small  grains  to  show  much  cleavage,  there  is 
often  a  tendency  for  a  single  cleavage  direction  to  be  revealed, 
though  the  smaller  areas  do  not  show  even  this. 

The  hardness  of  chalcocite  is  slightly  variable  in  different 
crystallographic  directions. 

UNKNOWN  "  TAPALPAITE  "  (GRAY)     ? 

COL.     Grayish  white.     With  galena,  grayish  white. 

HARD.     Low.  SURF.     Smooth. 

CHEM.     1.  HNOs.     Slowly  iridescent,  with  effervescence,  coated  with 

white.    Rubs  clean.    2.  KCN.    Slowly  darkens.    Rubs   clean.    3. 

HC1 .     4.  Aq.  Reg.     Instantly  effervesces  and  turns  iridescent. 

Fumes  tarnish  iridescent.    Rubs  clean  easily.    5.  FeCla.    Instantly 

iridescent,  brilliant.     Coated  thinly  with  white?    Rubs  clean.     6. 

KOH . 

DIFF.     Chem.  1.  ^S? 

ARGENTITE  Ag2S  ~ 

COL.     Grayish  white.     With  galena,  dull  pale  grayish  white;    with 

silver,  same;   with  tetrahedrite,  duller  gray,  no  brown  tinge;   with  3C 

enargite,  very  pale  greenish,  no  pink  tinge;    with  polybasite,  very 

pale  (greenish)  gray;    with  stephanite,  very  pale  greenish  yellow; 

with  dyscrasite,  very  dull  gray. 

HARD.    Low.     SURF.     Smooth,  but  easily  scratched.      H.  2-2.5  <=gn. 
CHEM.     1.  HNOs.    Slowly  light  brown;  fumes  tarnish  faintly;  rubs  off 

easily,  and  shows  structure  by  differential  etching.     2.  HNOs  cone. 

.    3.  KCN.     Slowly  or  quickly  dark  brown,  rubs  off  readily.  ^ 

Sometimes  only  faint  brown,  slowly.      4.  HC1 .     5.   HC1  cone.  «-J 

Instantly  tarnished  iridescent  by  the  fumes,   and  blackened  by 

acid,  forming  a  thick,  persistent  tarnish  film.     6.  Aq.  Reg.    In-  CrJ 

stantly  iridescent.     Fumes  tarnish  brighter  than  acid,  persistent.  t/) 

7.  FeCls    Slowly  turns  brown,  dries  iridescent;  rubs  off.     8.  KOH 

.    9.  NaOH .     10.  (NH<)aSx .  ^ 

DIFF.     Chem.  3,  6,  7.  ~* 

NOTE.     With  much  galena;  Aq.  Reg.  doea  not  tarnish  argentite  Q 

so  quickly  or  so  much.  Q^ 

STROMEYERITE        See  page  117.  < 

PEARCEITE        Bee  page  105.  £ 

107 


WHITE 

HARDNESS  Low 
GRAYISH  WHITE 
HNOs 
FeCl3  NEG. 


HC1  Neg. 


Q  STANNITE  SnCu2FeS4     (Hintze) 

^  [(Sn,  Cu,  Fe,  Zn)S] 

COL.     Pale  olive  gray.     With  galena,  pale  yellowish  brown,  or  greenish 

*•*»  gray;  with  silver,  pale  dull  brownish  gray,  or  yellowish  gray;  with 

W  tetrahedrite,  dull  brownish  gray.     Color  is  apparently  variable,  from 

^)  different  localities. 

**«                                   HARD.     Low.                       SURF.     Smooth.  H.  4  =  cp. 

CHEM.  1.  HNOs.  Quickly  brown,  then  brilliant  iridescent;  rubs  off. 
2.  HNOs  cone.  Darkens  quickly,  then  turns  green,  and  effervesces, 
washes  off  black  showing  solution  surface.  Rubs  clean,  showing 
differential  solution.  3.  KCN .  HC1 .  Fumes  tarnish  brown- 
ish. 4.  HC1  cone.  Same  as  HC1.  5.  Aq.  Reg.  Instantly  effervesces 
and  turns  iridescent;  develops  grains;  rubs  clean  easily.  6.  FeCls 

.     7.  KOH .     8.  NaOH .     9.  (NHO^S* .     10.  NH4OH 

.     11.  K3Fe(CN)6.     Slowly  faint  brown,  dries  darker,  rubs  off 

easily. 
DIFF.     Chem.  1,  7. 

BAUMHAUERITE  Pb4As6Si3 

COL.     White.     With  galena,  pale  grayish  white;    with   tetrahedrite 

light  grayish  white,  no  brown. 

HARD.     Low.  SURF.     Smooth.  H.  3. 

CHEM.     1.  HNOs.    Very  slowly  turns  some  portions  light  brown,  others 

much  less  easily;    rubs  off  easily.     2.  KCN .     3.  HC1 .     4. 

Aq.  Reg.     Instantly  iridescent,  blackens  with  effervescence;  rubs  to 

persistent  black.    5.  FeCl3 .    6.  KOH.     Quickly  iridescent,  with 

rapidly  changing  colors;  rubs  clean  easily. 
DIFF.     Chem.  1,  6. 


REALGAR  AsS 

COL.     White.     With    galena,    dull    grayish   white;     with   proustite, 

faintly  purplish  grayish  white.     Transparent  orange  by  oblique  light. 

HARD.     Low.  SURF.     Smooth.  H.  1.5-2. 

CHEM.     1.  HNOs.     Effervesces  but  does  not  change  color.     2.  HNO3 

cone.     Same.    3.  KCN .    4.  HC1 .     5.  Aq.  Reg.     Effervesces, 

turns  brown  and  darkens,  rubs  to  rough  gray.     6.  FeCls .     7. 

KOH.     Instantly  brown,  then  blackens  and  dissolves  very  rapidly. 

8.  (NH4)2SX .     9.  K3Fe(CN)6 . 

DIFF.     Col.     Chem.  1,  7. 

NOTE.  Realgar  with  lorandite  from  Macedonia  is  transparent 
red  by  oblique  light.  Also  is  blackened,  without  effervescence, 
by  HNOs;  and  is  slowly  blackened  by  KOH. 


CROOKESITE  (CuTlAg)2Se 

COL.     Grayish  white.     With  galena,  grayish  (brownish)  white;   with 

tetrahedrite,  practically  the  same. 

HARD.     Low  (medium) .     SURF.     Smooth.  H.   =  2.5-3. 

CHEM.     1.  HNOs.    Slowly  faint  brown.    Fumes  instantly  light  brown. 

Rubs  clean  easily.      2.  KCN ?  (test  not  positive).      3.  HC1 . 

4.  Aq.  Reg. .     5.  FeCla .     6.  KOH ?  (possibly  very  faint 

brown,  doubtful). 
DIFF.     Col.     Chem.  1. 


108 

1 


RA 


I 


m 

FREIESLEBENITE         See  page  134. 
GUANAJUATITE         See  page  120. 
ANDORITE        See  page  134. 
UNKNOWN  (near  Andorite)         See  page  134. 


0 

z 

E 


109 


I 


LU 
Q 


WHITE 

HARDNESS  Low 
GRAYISH  WHITE 
HNO« 
FeCla  NBG. 


Fumes  HC1 


.  CYLINDRITE  3  PbSnS2  +  SnFeSb2S8 

COL.     White.     With  galena,  pale  grayish  white;    with  tetrahedrite, 
^,  almost  the  same,  but  no  brown. 

^  HARD.     Low.  SURF.     Smooth.  H.  2.5-3. 

w  CHEM.     1.  HNOs.    Slowly  brown,  then  iridescent;  rubs  clean.    Fumes 

Q  tarnish  slightly.     2.  KCN .      3.  HC1 .     Fumes  tarnish  pale 

QJ  brown.     4.  Aq.  Reg.     Immediately  brown,  then  iridescent;    rubs 

{>  clean  easily.  Fumes  tarnish.    5.  FeCla .    6.  KOH.   Slowly  brown, 

then  iridescent;  rubs  clean  easily. 
DIFF.     Chem.  1,  6. 

FRANKEITE  3  PbSnS2  +  Pb2FeSb2S8 

COL.     White.     With  galena,  creamy  grayish  white;   with  silver,  pale 

grayish  white;  with  tetrahedrite,  very  close,  but  a  little  lighter. 
HARD.     Low.  SURF.     Smooth.  H.  1-2. 

CHEM.     1.   HNOa.     Rather  quickly  brown,  then  brilliant  iridescent; 

rubs  clean  easily.    2.  KCN .    3.  HC1 .   Fumes  tarnish  slightly. 

4.  Aq.  Reg.    Instantly  iridescent,  effervesces  a  moment;   rubs  clean 

easily.    Fumes  tarnish  bright.    5.  FeCla .    6.  KOH.    Slowly  pale 

brown,  rubs  clean. 
DIFF.     Chem.  1,  6. 

BROGNIARDITE  PbAg2Sb2S6  ? 

COL.  White.  With  galena,  pale  (bluish)  white;  with  tetrahedrite, 
distinctly  bluish  white. 

HARD.     Low.  SURF.     Smooth.  H.  =  gn? 

CHEM.  1.  HNO3.  Slowly  pale  brown  (differentially) ;  rubs  clean  easily. 
2.  KCN.  Slowly  faint  brown  (uniform) ;  rubs  clean  easily.  3.  HC1. 
Very  faint  brown,  slowly.  Fumes  tarnish  light  brown.  Rubs  clean 
easily.  4.  Aq.  Reg.  Immediately  effervesces  and  turns  iridescent, 
darkening  and  developing  a  white  coating.  Fumes  tarnish  brilliant 
iridescent.  Rubs  to  gray  rough  surface.  Fumes  rub  clean.  5. 

FeCla .    6.  KOH.    Instantly  bright  iridescent;  rubs  clean  easily, 

showing  etched  surface. 

DIFF.     Chem.  1,  6. 

NOTE.     Close  to  jamesonite. 


JAMESONITE  Pb2Sb2S6 

COL.  White.  Mixture  of  grayish  and  pale  creamy  whites,  the  gray 
decidedly  harder.  Act  about  the  same  chemically  and  appear  to  be 
differently  oriented  individuals.  With  galena,  decidedly  grayish 
creamy  white,  and  almost  same;  with  silver,  same  as  with  galena; 
with  tetrahedrite,  slightly  grayer,  and  pure  white. 

HARD.     Low.  SURF.     Smooth.  H.  2-3. 

CHEM.  1.  HNOs.  Instantly  brown,  then  black.  White  coating  shown 
by  oblique  light.  Rubs  easily  to  brilliant  iridescent,  persistent.  2. 
KCN  -  .  3.  HC1  -  .  Fumes  tarnish  slowly  bright;  rubs  easily  to 
faint  brown,  persistent.  4.  Aq.  Reg.  Rather  quickly  brown,  with 
effervescence,  then  blackens.  Gray  quicker  than  white.  Yellowish 
coating  formed  ;  rubs  to  gray  rough  surface.  Fumes  tarnish  brilliant 
iridescent.  5.  FeCk  -  .  6.  KOH.  Slowly  blue  and  purple  tarnish, 
white  less  touched,  and  some  gray  grains  more  than  others. 

DIFF.     Chem.  1,  4,  6. 


1 


RA 


ZINKENITE  PbSbzS, 

COL.  White.  With  galena,  pale  grayish  white;  with  tetrahedrite, 
lighter  grayish  white,  no  brown ;  with  j  amesonite,  about  same,  may 
be  a  little  bluer.  Color  slightly  variable,  due  to  different  orienta- 
tion of  individuals. 

HARD.     Low.  SURF.     Smooth.  H.  3  +. 

CHEM.  1.  HNOs.  Quickly  blackens  with  effervescence,  rubs  to  irides- 
cent gray,  rough.  2.  KCN .  3.  HC1 .  Fumes  slowly  tarnish 

brown.  4.  Aq.  Reg.  Instantly  brown,  then  black;  rubs  to  gray 

rough  surface.  Fumes  tarnish  instantly.  5.  FeCla .  6.  KOH. 

Some  grains  instantly  iridescent;  some  untouched.  Rubs  easily  to 
pale  colors. 

DIFF.     Chem.  1,  4,  6. 


0 

z 

K 


I 

V) 
CO 
LU 
Z 

Q 


111 


WHITE 

HARDNESS  Low 
GRAYISH  WHITE 
HN08 
FeGl«  N«cu 


HC1 


I 
I 


ALABANDITE        See  page  96. 
COSALITE        See  page  122. 


ss 
I 

I 


112 


RA 


... 


d 

z 

E 


1 


UJ 

Q 


113 


1 


WHITE 

HARDNESS  Low 
BLUISH  WHITE 
HNOjNuo. 


KOH  Neg. 


TIEMANNITE  HgSe 

COL.     White.     With  galena,  distinctly  pale  blue;    with  silver,  pale 

blue,  darker  than  with  galena. 

HARD.     Low.  SURF.     Smooth.  H.  2.5. 

CHEM.     1.  HNO3  -  .     2.  HNO3  cone.  -  .     3.  KCN  -  .      4.  HC1  -  . 

5.  HC1  cone.  -  .     6.  Aq.  Reg.    Rapidly  blue,  red,  iridescent,  then 
coated  with  orange  yellow,  rubbing  to  uniform  gray.     7.  FeCls  -  . 
8.  KOH  -  .     9.  (NH4)2SX.      Very  slowly  brown,  rubs  clean.     10. 
NH4OH—  .     ll.K4Fe(CN)e  -  .      12.  K3Fe(CN)6  -  .      13.  Iodine. 
Bright  iridescent;   rubs  to  persistent  gravish  green. 

DIPF.     Chem.  1,  6,  7. 

ONOFRITE  Hg(SSc) 

COL.  White.  With  galena,  pale  bluish  white;  with  cuprite,  bluish 
white,  makes  latter  look  creamy;  with  tiemannite,  same.  Shows 
intergrowth  of  whiter  and  browner  portions,  showing  crystal  out- 
lines. May  be  due  to  different  orientation. 

HARD.     Low.  SURF.     Smooth.  H.  2.5. 

CHEM.  1.  HNOs  -  .  2.  KCN.  Faintly  blue  and  roughens.  Rubs 
clean,  showing  shallow  solution  pit.  3.  HC1  -  .  4.  Aq.  Reg. 
Quickly  iridescent,  growing  brilliant;  effervesces;  finally  coated  with 
yellow.  Rubs  clean,  showing  deeply  etched  surface.  5.  FeCls  -  . 

6.  KOH  -  . 
DIFF.     Chem.  2,  4,  5. 


POLYARGYRITE 

COL.     Bluish  white.     With  galena,  pale  blue;    with  cuprite,  bluish 

greenish  gray,  grayer  than  cuprite. 

HARD.     Very  low.  SURF.     Smooth.  H.  2.5  <3C  cp. 

CHEM.  1.  HNOa  -  .  Fumes^tarnish.  When  with  chalcopyrite,  tar- 
nishes slightly  brown  and  iridescent.  Rubs  clean  easily.  2.  KCN. 
Instantly  turns  brown.  Dries  brilliant  iridescent  when  rinsed  off. 
Rubs  clean  rather  easily.  3.  HC1  -  .  4.  Aq.  Reg.  Instantly  bril- 
liant iridescent,  with  effervescence.  Fumes  tarnish  brilliant  iri- 
descent. Rubs  clean  easily.  5.  FeCla.  Rather  quickly  darkens  and 

r  ^  appears  to  roughen.     Rinses  off  to  brilliant  iridescent.     Rubs  clean 

Cq  easily.     6.  KOH  -  . 

S-,  DIFF.     Chem.  2,  5. 

1C;  STUTZITE                                             Ag4Te  ? 

^  COL.     White.     With  galena,  very  pale  bluish  white. 

•*•  HARD.     Low.                       SURF.     Smooth.                      H.  =  tellurium. 

^  CHEM.     1.  HNO3  -  .     2.  KCN  -  .     3.  HC1  -  .     4.  Aq.  Reg.    Effer- 

5j  vesces  and  slowly  turns  bright  iridescent  then  dark.     Rubs  easily  to 

ff)  gray  iridescent  surface,  roughened,  and  spotted  with  minute  clean 

<  areas.     5.  FeCla  -  •.     6.  KOH  -  . 

j^  DIFF.     Chem.  4. 

3  UNKNOWN  (silver  mineral,  Tonopah,  Nev.)  ? 

^  COL.     Bluish  white.     With  galena  (grayish),  bluish  white;  with  silver, 

bluish  white. 

HARD.     Low.  SURF.     Ragged.  H  <  silver. 

CHEM.    1.  HNO3  -  .   Fumes  tarnish  slightly.    2.  KCN  -  .    3.  HC1  -  . 
4.  HC1  cone.  -  .   Fumes  tarnish  slightly.   5.  Aq.  Reg.   Instantly  bril- 
liant iridescent.     Fumes  same,  rubs  clean  easily.     6.  FeCla.     Slowly 
darkens  and  turns  iridescent.     Rubs  clean  easily.     7.  KOH  -  . 
DIFF.     Chem.  2,  6. 

fY>  NOTE.     Same  as  polyargyrite  except  that  it  does  not  effervesce 

*U  with  Aq.  Reg.,  and  is  not  attacked  by  KCN. 


COVELLITE       See  page  58. 
KALGOORLITE       See  page  124. 
RATHITE       See  page  141. 
CINNABAR       See  page  141. 


114 


RA 


KOH 
PROUSTITE  AgsAsSi 

COL.     Bluish  white.     With  galena,  bluish  white;  with  cuprite,  about 

the  same.     Transparent  brilliant  red  with  oblique  light. 
HARD.     Low.                      SURF.     Smooth.  H.  2.5  =  gn. 

CHEM.     1.   HNO3 .    2.   HNOs  cone. .     3.   KCN.    Slowly  light 

brown,  developing  scratches.     When  rinsed  off,  without  rubbing, 

shows  little  or  no  orange  yellow  jjoating,  rubs  clean  easily.     4. 

HC1 .     5.  HC1  conc.-r— .     6.  Aqf  Reg.     Brown,  then  iridescent, 

then  effervesces  slowly,  and  blackens.     Rubs  easily  to  persistent 

light  brown.     Fumes  tarnish.     7.  FeCls.     Slowly  faint  tarnish?     8. 

KOH.     Instantly  brown,  quickly  darkening.     Rubs  to  pale  yellowish 

roughened    surface.     9.    NaOH.    Same    as    KOH.    10.    (NH4)2SX. 

Slowly  faint  brown,  rubs  off  clean.     11.  NH*OH .     12.  K*Fe(CN)« 

.     13.  KsFe  (CN)6 . 

DIFF.     Col.     Chem.  3.  Jr 

NOTE.     The  presence  of  some  Sb  probably  accounts  for  any  coat- 
ing with  KCN.  Q 

PYRARGYRITE  AgsSbSs  £ 

COL.     Bluish  white.     With  galena,  pale  bluish  white;  with  proustite, 

slightly  lighter?     Transparent  brilliant  red  by  oblique  light. 
HARD.     Low.                      SURF.     Smooth.  H.  2.5  =  gn. 

CHEM.     1.   HNOs .     2.    HNOs  cone. .     3.    KCN.    Slowly  light 

brown,  developing  scratches.     When  rinsed  off,  shows  orange  yellow 

coating,  rubs  off,  leaving  solution  pit.     4.  HC1 .     5.  HC1  cone. . 

6.  Aq.  Reg.     Brown,  then  iridescent,  then  effervesces  slowly  and 
blackens.     Rubs  easily  to  light  brown,  persistent.     Fumes  tarnish. 

7.  FeCls.     Dissolves  (?)   slightly,   but  does  not  change  color.     8. 
KOH.     Instantly  iridescent,  and  immediately  blackens  and  dissolves. 
Rubs  off  to  show  solution  pit  colored  pale  brownish  yellow.     9. 
NaOH.  Same  as  KOH.    10.  (NH4)2SX.    Slowly  faint  brown,  rubs  off 
clean.     11.  NH4OH .     12.  K4Fe(CN)8 .     13.  KsFe(CN)6 . 

DIFF.     Col.     Chem.  3. 

UNKNOWN  (Bluish  white,  with  sternbergite,  from  Joachimsthal)  ^ 

COL.  Bluish  white.  With  galena,  pale  bluish  white;  with  silver,  de- 
cidedly bluish  white. 

HARD.     Very  low.  SURF.     Smooth.  H.   =  cc.? 

CHEM.  1.  HNOs .  2.  KCN.  Darkens  to  gray,  develops  structure. 

3.  HC1 .  4.  Aq.  Reg  Black  and  iridescent,  persistent.  5.  KOH. 

Rapidly  iridescent,  then  black.  Rubs  clean  showing  solution  sur- 
face. 6.  FeCls . 

DIFF.     Col.     Chem.  2,  4. 

NOTE.     Possibly  near  miargyrite. 

VRBAITE  TlAs2SbS6 

COL.     Bluish  white.     About  like  cuprite.     Transparent  red  by  oblique 

light. 

HARD.     Low.                      SURF.     Smooth. 
CHEM.     1.  HNOs .    2.  KCN .    3.  HC1 .    4.  Aq.  Reg.    Quickly 

effervesces  and  blackens.     Rubs  to  gray,  rough  surface.     5.  FeCls 

.     6.    KOH.     Instantly  iridescent.     Rubs  to  persistent   gray, 

roughened  surface. 
DIFF.     Chem.  2. 

MIARGYRITE  AgSbS2  Q     j 

COL.     White.     Faintly  mottled,  in  various  shades,  like  chalcocite.  *p     « 

With  galena,   bluish  white;    with  silver,   bluish  white.     Deep  red  "     *  £> 

transparent  with  bright  oblique  light.  ^ 

HARD.     Low.  SURF.     Smooth.  H.  2-2.5.  C 

CHEM.     1.  HNOs .     2.  KCN.      Slowly  pale  brown,  rubs  faint,  per-  ( 

sistent.    3.  HC1 .    4.  Aq.  Reg.    Quickly  brown,  with  effervescence, 

then  iridescence.     Yellowish  white  coating  formed.     Rubs  to  gray,  y* 

roughened  surface.     Fumes  tarnish  slowly,   bright  iridescent.     5.  '  CT 

FeCls .     6.   KOH.     Instantly  iridescent,  with  rapid  change  of  J 

colors  to  higher  orders,  the  last  stage  brownish  gray  and  dark  brown.  )  *•* 

Rubs  to  gray,  rough  surface,  showing  differential  solution;    white  «  Z 

usually  more  resistent. 

DIFF.     Col.     Chem.  2,4.  ) 

STEPHANITE         See  page  142.  9 

115  - 

d 


WHITE 

HARDNESS  Low 
BLUISH  WHITE 
HNOs 


KCN  Neg 


UNKNOWN  "  Purple  Galena." 

COL.     Pale  purplish  gray.     With  galena  or  silver,  pale  purplish  gray; 

with  coloradoite,  somewhat  bluer. 

HARD.     Low.     SURF.     Smooth  but  with  triangular  H.  ? 

cleavage  pits  like  galena. 

CHEM.     1.  HNOs.    Bright  iridescent.    2.  KCN .    3.  HC1.    Slowly 

brown,  faint.  Fumes  tarnish  bright  iridescent.  4.  Aq.  Reg.  In- 
stantly tarnishes  bright  which  quickly  darkens  to  deep  blue;  rubs 
clean  easily.  5.  FeCl2.  Slowly  iridescent,  rubs  off  clean.  6.  KOH 

DIFF.'  Col.     Surf. 

NOTE.     Reactions  may  be  modified  by  the  presence  of  calcite,  or 
native  silver  and  niccolite,  in  the  specimens  tested. 

PLENARGYRITE  »  (soft)  ? 

COL.     Bluish  white.     With  galena,  pale  bluish  white. 

HARD.     Low.  SURF.     Smooth.  H  <  plenargyrite. 

CHEM.     1.  HNOa.     Instantly  iridescent,  persistent.     2.  KCN .     3. 

HC1.     Darkened  and  etched;  fumes  tarnish.     Rubs  clean  easily.     4. 

Aq.  Reg.    Instantly  effervesces;  turns  iridescent,  then  black.     Rubs 

black  and  rough.     5.  FeCls.     Slowly  dark  brown,  iridescent.     Rubs 

clean  easily.     6.  KOH . 

DIFF.     Chem.  3,  6. 

NOTE.     Occurs  with  plenargyrite  exactly  the  same  as  "schap- 
bachite"  (soft),  with  schapbachite. 

•  •  SCHAPBACHITE  "  (soft)  ? 

U4  COL.     Bluish  white.     With  galena,  bluish  white? 

f^  HARD.     Low.  SURF.     Smooth.  H.  <  schapbachite. 

JN  CHEM.     1.   HNO3.     Instantly  blackens,  persistent.     2.   KCN .     3. 

I^j  HC1.   Instantly  darkened  and  etched.    Rubs  clean.   4.   Aq.  Reg.   In- 

N.  stantly  blackens,  persistent.     5.  FeCls.     Rather  slowly  brown,  then 

^  bright  and  iridescent.     Rubs  clean  easily.    6.  KOH.     Slowly  brown. 

Rubs  clean  easily. 
|g  DIFF.     Chem.  3,  6. 

I 

hj 

QQ  COLORADOITE.    See  page  106. 


| 


I 


RAY. 


KCN 


CUPRITE  Cu2O 

COL.  White.  With  galena,  decidedly  bluish  white;  with  proustite» 
the  same  color.  Transparent  deep  red  by  oblique  light. 

HARD.     Medium.      SURF.     Shiny  but  usually  pitted.      H.  3.5-4>  cc. 

CHEM.  1.  HNOs.  Instantly  plated  with  metallic  copper,  which  blackens 
and  appears  to  dissolve  immediately,  with  effervescence.  On  wash- 
ing off  and  drying  without  rubbing,  a  film  of  copper  is  seen  on  the 
surface,  pink  by  oblique  light.  Rubs  off  easily,  leaving  a  brilliant 
iridescent  surface  on  some  grains,  and  some  blackened.  Fumes 
tarnish  iridescent.  2.  HNOs  cone.  Effervesces,  blackens  and  dis- 
solves. 3.  KCN.  Quickly  etches  and  develops  a  "cleavage"  or 
crystal  structure  (?) .  4.  HC1.  Instantly  blackens  and  is  coated  with 
white  (seen  by  oblique  light);  rubs  off.  Fumes  tarnish  brilliant 
iridescent.  5.  HC1  cone.  Same  as  HC1.  6.  Aq.  Reg.  Same  as  HC1. 

7.  FeCl3.    Rather  quickly  persistent  dark  iridescent.    8.  KOH .    9. 

NaOH .     10.  (NH4)2SX.     Quickly  blackens  and  turns  iridescent; 

shows  rough  solution  surface  on  rubbing. 

DIFF.     Col.     Chem.  1  and  4. 

NOTE.     Practically  always  carries  intermixed  native  copper. 


STROMEYERITE  (AgCu)2S 

COL.  White.  With  galena,  bluish  grayish  white;  with  chalcocite, 
purplish. 

HARD.     Low  (very  low).     SURF.     Smooth  or  "ragged."  H.  2.5-3  <  cc. 

CHEM.  1.  HNOs.  Darkened  slightly,  and  etched,  developing  a  cleav- 
age on  some  grains.  Fumes  tarnish  brown,  some  grains  more  than 
others.  Tarnish  washes  off.  2.  KCN.  Quickly  brown,  dries  darker, 
and  rubs  off  easily,  leaving  a  clean,  faintly  creamy  white,  surface. 

3.  HC1 .  Fumes  slowly  form  a  narrow  tarnish  ring  around  the  drop. 

Rubs  off.  4.  HC1  cone.  Instantly  dark  and  rough.  Fumes  tarnish 
bright  iridescent.  Rubs  off  hard,  leaving  a  roughened  surface.  5. 
Aq.  Reg.  Quickly  speckled  with  black,  rubs  off  to  show  slight  rough- 
ening (?).  6.  FeCls.  Instantly  bright  iridescent,  showing  structure. 
Rubs  easily  to  pale  blues,  and  white,  with  a  shallow  solution  pit.  7. 
KOH . 

DIFF.     Hard.     Col.     Chem.  1. 


CHALCOCITE         See  page  107. 

09         « 

0  J 

POLYARGYRITE         See  page  114.  22 

E  I 

BROGNIARDITE         See  page  110.  „ 


3 

0 

117  D 


WHITE 

HARDNESS  Low 

CREAMY  WHITE 

SAME  AS  SILVER,  OB  WHITER 

FeCls 


s 

I 

I 


No  Eflf.  Aq.  Reg. 


(HESSITE  ?)  ? 

COL.     White.     With  galena,  pale  creamy  white;  with  silver,  same. 

HARD.     Low.  SURF.     Smooth.  H.  2-3  <  gn. 

CHEM.  1.  HNOs.  Instantly  blackens  with  effervescence;  rubs  to  gray, 
and  with  continued  rubbing  to  white  again,  with  roughened  surface. 
2.  KCN  -  ?  3.  HC1  -  .  4.  Aq.  Reg.  -  .  5.  FeCls.  Slowly  bright 
iridescent,  persistent.  6.  KOH  -  .  7.  NaOH  -  .  8.  (NH4)2SX. 
Quickly  light  iridescent;  rubs  off  easily.  9.  Iodine.  Fumes,  in- 
stantly  brilliant  colors,  rub  off  easily.  Liquid,  gray  iridescent  or 
yellow,  persistent. 

DIFF.     Surf.     Chem.  1,  4. 

NOTE.     Differs  in  properties  from  crystallized  hessite  from  Felso- 
banya,  Hungary.     (See  page  138.) 


SILVER  Ag 

COL.     White.     With  galena,  pale  creamy  white. 

HARD.     Low.  SURF.     Metallic,  smooth.  H.  2.5-3. 

CHEM.  1.  HNOs.  Blackens  quickly,  due  to  the  formation  of  a  very 
rough  solution  surface,  often  showing  crystalline  etch  figures.  2. 
KCN  -  .  3.  HC1  -  .  Fumes  tarnish  white,  washes  off.  4.  HC1 
cone.  same.  5.  Aq.  Reg.  Tarnishes  quickly  yellow,  red,  blue,  bril- 
liant colors,  persistent.  6.  FeCls.  Quickly  bright  iridescent,  per- 
sistent. 7.  KOH  -  .  8.  (NH4)2Sx  -  .  Fumes  tarnish  brownish. 
9.  NH4OH  -  .  10.  Iodine.  White  coating,  rubs  off  bright  iridescent. 

DIFF.     Col.     Surf.     Chem.  1,  5. 


ALTAITE        See  page  128. 


i 
1 

^  118 

i 


GRAY. 


t 


Eff.  Aq.  'Reg. 


HUNTILITE  AgaAs  ? 

COL.  White.  With  galena,  pale  creamy  white;  with  silver,  practi- 
cally same  color;  with  algodonite  (cream),  nearly  pure  white. 

HARD.     Medium.  SURF.     Smooth. 

CHEM.  1.  HNOs.  Instantly  blackens,  with  vigorous  effervescence; 
forms  very  rough  surface.  2.  KCN.  Slowly  brown,  then  black. 

Parts  very  resistant;  rubs  clean  to  show  solution  pits.  3.  HC1 . 

Fumes  tarnish  deep  colored,  persistent.  4.  Aq.  Reg.  Instantly  iri- 
descent; effervesces,  turns  bright  brown;  rubs  to  bright  iridescent, 
persistent.  5.  FeCls.  Instantly  iridescent,  persistent.  6.  KOH . 

DIFF.     Chem.  2. 

NOTE.     Only  specimen  available  is  much  altered,  to  pale  yellowish 
gray  mineral  in  dendritic  veinlets. 


0 

1 

(0 

« 

<0 

u 

S 


CO 


I3 
1° 


! 


119 


WHITE 

HARDNESS  Low 
CREAMY  WHITE 
SAME  AS  SILVER,  OR  W: 
FeCl*  NEQ. 


KOH  Neg. 

(MATILDITE  ?)  ? 

COL.     White.     With  galena,  faint  creamy  white,  like  silver;    with 

silver,  practically  pure  white. 
j**  HARD.     Low.  SURF.     Smooth. 

CHEM.    1.  HNOs.    Slowly  bright  yellowish  brown;  rubs  to  roughened 

surface.     2.    KCN .     3.    HC1 .     4.    HC15  cone. .      5.   Aq. 

Reg.    Tarnishes  and  blackens  quickly;  rubs  to  rough,  dark  surface. 

UJ  6.  FeCU .     7.  KOH . 

^  DIFF.     Chem.  1,  4. 

Ejj  NOTE.     Differs  from  true  matildite,  see  page  140. 

GUANAJUATITE  Bi2Se» 

^  COL.     White.     With  galena,  pale  creamy  white;   with  silver,  practi- 

ta  cally  white.     Shows  intergrowth  of  white  and  pale  creamy  gray 

^  (orientation  different  ?). 

^*  HARD.     Low.  SURF.     Smooth.  H.  2.5-3.5. 

Q>  CHEM.    1.  HNOa.    Rapidly  brilliant  iridescent;  rubs  clean  easily  leaving 

ZJj  rough    surface,    white   portions   little   touched.     2.    KCN .     3. 

y*  HC1 .    4.  HC1  cone. .    5.  Aq.  Reg.    White  untouched;   grayer 

O  part  instantly  iridescent,  with  vigorous  effervescence,  then  orange 

yellow    (?)    coating   formed,    persistent,    with   rough    surface.     6. 

FeCl3 .     7.  KOH . 

DIFF.     Chem.  1,  4. 


CHIVIATITE  Pb2Bi6Su 

rr>  COL.     Creamy  white.     With  galena,  pale  creamy  white;   with  silver, 

faintly  grayish  white. 
HARD.     Low.  SURF.     Smooth. 


s*J  CHEM.    1.  HNOs.    Slowly  tarnishes  iridescent  with  slow  effervescence. 

I^i  At  last  dark  grayish.     Thinly  coated  with  white.     Rubs  clean  easily, 

showing  slightly  roughened  surface.     2.  KCN .     3.  HC1 .     4. 

Aq.  Reg.    Quickly  brown,  with  vigorous  effervescence.    Coated  with 

•^  white.     Rubs  clean  easily,  showing  a  pitted  surface.     5.  FeCls . 

•El  6.  KOH . 

C/5  DIFF.     Chem.  1. 

a 

BISMUTHINITE        See  page  130. 
GALENOBISMUTITE        See  page  130. 


I 

I 


^    * 

i 


120 


GRAY. 


KOH 


WITTICHENITE 

COL.  White.  With  galena,  creamy  white;  with  silver,  practically 
same. 

HARD.     Low.  SURF.     Smooth.  H.  3.5. 

CHEM.  1.  HNOs.  Turns  faintly  yellowish,  persistent,  when  washed  off. 

Fumes  tarnish  slowly.  2.  KCN .  3.  HC1  cone. .  4.  Aq.  Reg. 

Rather  quickly  bright  brown  with  slow  effervescence.  Fumes  in- 
stantly tarnish  brown.  Rubs  clean  rather  easily.  5.  FeCla .  6. 

KOH.  Slowly  faint  brown,  rubs  clean. 

DIFF.     Chem.  1,  4. 


121 


WHITE 

HABDNESS  Low 
CREAMY  WHITE 
DARKER  THAN  SILVER 
HNO, 
FeCls  NEQ. 


COSALITE  Pb2Bi2Ss 

COL.  White.  With  galena,  creamy  white;  with  silver,  creamy  white. 
Mixture  of  creamy  white  and  pale  gray  needles,  due  possibly  to 
difference  in  orientation  of  individuals. 

HARD.     Low.  SURF.     Smooth.  H.  2.5-3. 

CHEM.  1.  HNOs.  Creamy  part  instantly  blackened,  with  effervescence; 

gray  hardly  touched.  2.  KCN .  3.  HC1.  Slowly  faint  yellowish, 

rubs  clean  easily.  4.  Aq.  Reg.  Instantly  effervesces  and  tarnishes 
iridescent,  then  blackens;  fumes  tarnish  bright  brown;  rubs  to  gray 

rough  surface.  5.  FeCl3 .  6.  KOH.  Rather  quickly  bright  brown, 

Q>  .then  iridescent. 

DIFF.     Chem.  1,  6. 

Jj^ 

JC  EMPLECTITE  CuBiS2 

^  COL.     White.     With   galena,    decidedly    creamy    (brownish);     with 

.  silver,  pale  brownish  cream. 

>*  HARD.     Low.  SURF.     Smooth.  H.  2. 

]2J  CHEM.    1.  HNOs.    Rather  slowly  light  brown,  with  slight  effervescence. 

Fumes  tarnish  slightly.     Rubs  clean.     2.  KCN .     3.  HC1 .     4. 

Aq.  Reg.    Rapidly  blackens,  with  effervescence.    Rubs  to  gray,  with 

U^                                                         rough    solution    surface.     Fumes    tarnish    yellowish    brown.     5. 
^  FeCls .    6.  KOH.    Same  as  HNO3,  but  more  slowly.    7.  (NH^Sx 

>^  DIFF.     Chem.  1,  6. 

METACINNABARITE  HgS 

COL.     White.     With  galena,   pale  creamy  and  faint  purple;    with 

silver,  same  as  with  galena.     Intergrowth  of  pale  blue  (cinnabar  ?) 

and  pinkish  purple  with  creamy  white. 
U}  HARD.     Low.  SURF.     Smooth.  H.  3. 

t^  CHEM.     1.  HNOs.    Very  slowly  faintly  yellowish.     2.   KCN .    3. 

N*,  HC1  cone.    Same  as  HNO3.    4.  Aq.  Reg.    Quickly  blackens,  with 

effervescence,  leaving  very  rough  surface.     5.  FeCl3 .     6.  KOH. 

Same  as  HNO3. 
l£  DIFF.     Chem.  1. 

C/3  SYLVANITE  AuAgTez 

I^J  COL.     White.     With  galena,  decided  pale  creamy  white;   with  silver, 

O  pale  cream. 

i^  HARD.     Low.  SURF.     Smooth.  H.  1.5-2. 

QQ                                                        CHEM.    1.  HNOs.    Instantly  bright  brown,  iridescent  around  edges,  per- 
sistent; develops  cleavage.     2.  KCN .     3.  HC1 .     4.  Aq.  Reg. 

-^?  Slowly  effervesces,  tarnishing,  and  dissolving  where  bubbles  start. 

Q  Rubs  clean  to  show  pits.     Fumes  tarnish.     With  alabandite,  in- 

«^  stantly  effervesces  and  etches,  brown,  persistent.     5.  FeCls .     Or 

Jjj  occasionally  very  slowly  faint  brown  (doubtful).     6.  KOH . 

DIFF.     Chem.  1,  6. 

8 
S5 


122 


GRAY. 


5 
| 

FRANKEITE         See  page  110. 
WITTICHENITE          See  page  121. 
AIKINITE         See  page  101. 
CHIVIATITE         See  page  120. 
FREIESLEBENITE         See  page  134. 


123  „ 

6 
a 
f) 


WHITE 

HARDNESS  Low 

CREAMY  WHITE 

DARKER  THAN  SILVER 

HNOa 

FeCla 


HC1  Neg. 


MELONITE 

COL.  Cream.  With  galena,  decidedly  creamy;  with  silver,  de- 
cidedly creamy. 

HARD.     Low.  SURF.     Smooth.  H.  1-2  >  gold. 

CHEM.  1.  HNOs.  Instantly  effervesces  and  blackens;  rubs  to  irides- 
cent and  gray;  showing  some  parts  not  discolored.  2.  KCN .  3. 

HC1 .  4.  Aq.  Reg. .  5.  FeCls.  Slowly  darkens  to  light  brown, 

rubs  to  roughened  surface.  6.  KOH .  7.  NaOH .  8. 

(NH<)2SX . 

DIFF.     Chem.  1,  4 

CALAVERITE  AgAuTej 

COL.  Creamy  white.  With  galena,  decidedly  deep  cream  color;  with 
silver,  very  pale  cream;  with  melonite,  very  close,  nearly  the  same. 

HARD.     Low.  SURF.     Smooth.  H.  2.5. 

CHEM.  1.  HNOs.  Quickly  bright  brown  with  slow  effervescence;  rubs 
to  light  brown  with  iridescent  edges.  Develops  delicate  cleavage  in 

crystals.     2.  KCN .     3.  HC1 .     4.  Aq.  Reg.    Effervesces  and 

slowly  tarnishes  green.  5.  FeCls.  Slowly  brown,  then  bright  irides- 
cent; rubs  clean  to  show  solution  pit.  6.  KOH.  Slowly  tarnished 
brownish;  rubs  off  to  pale  yellow.  7.  NaOH ? " 

DIFF.     Chem.  1,  4. 

NOTE.     Krennerite  is  the  same  as  calaverite. 

KALGOORLITE  HgAu2Ag6Te«  ? 

COL.     White.     With  galena,  pale  creamy  brown ;  with  silver,  dull  pale 

creamy  gray;  with  calaverite,  decidedly  paler  creamy  (gray). 
HARD.     Low.  SURF.     Smooth. 

CHEM.    1.  HNOs.    Very  slowly  faint  brown.    2.  KCN .    3.  HC1 . 

4.  Aq.  Reg.    Instantly  effervesces  and  turns  iridescent,  at  last  bril- 
liant, with  a  persistent  white  coating.     Covered  with  minute  round 
*^  pits  formed  by  etching.    5.  FeCls.    Rapidly  brilliant  iridescent,  per- 

^  sistent.     6.  KOH . 

C/}  DIFF.     Col.     Chem.  1,  5. 

*4  SYLVANITE  ?         See  page  122. 

Q  ARSENIC         See  page  136. 

ft5  HESSITE         See  page  138. 

COPPER         See  page  67. 

!5  TAPALPAITE         See  page  125. 

PETZITE         See  page  137. 


124 


i 


GRAY. 


HCl 


DOMEYKTTE  (Mixture)  '     CtiaAs  (Sb)? 

x  COL.    White.    With  galena,  pale  yellowigh  creamy  gray  and  very  pale  purple; 

with  silver,  same  as  with  galena. 

HARD.     Low  or  medium.  SURF.    Smooth.  H.  3-3.5. 

CHEM.  1.  HNOs.  Effervesces  and  blackens  immediately,  dissolves.  2.  HNOs  cone. 
Same.  3.  KCN.  -  .  Purple  portion  turned  pinkish.  4.  HCl.  Develops  struc- 
ture in  white  part;  purple  -  .  5.  HCl  Cone.  Same.  6.  Aq.  Reg.  Instantly 
effervesces  and  etches,  developing  a  structure.  Fumes  tarnish  iridescent. 
Rubs  clean  easily.  7.  Feds-  Instantly  dark  iridescent;  rubs  to  clean  rough 
surface.  8.  KOH.  Tarnishes  rapidly  to  brilliant  iridescent;  rubs  clean  easily; 
purple  tarnishes  first.  9.  (NH4)2SX.  Quickly  darkens,  dissolves  white  quicker 
than  purple.  10.  NH4OH.  Purple,  bright  yellowish  brown,  white  hardly 
touched.  11.  KiFe(CN)8.  Purple  turns  black,  white  turns  brown,  persistent. 
12.  K3Fe(CN)6.  Same  as  11. 
DIFF.  Chem.  1,  2. 

NOTE.  Only  one  specimen  showed  this  mixture.  Three  others  show  the 
same  components  as  algodonite. 

BISMUTH  Bi 

COL.  Creamy  white,  tarnishing  very  rapidly  pale  yellow,  persistent.  With 
galena,  pinkish  creamy  white;  with  silver,  pale  pinkish  creamy  white,  not  so 
yellow  as  with  galena. 

HARD.     Low.  SURF.     Metallic,  smooth.  H.  2-2.5  <  silver. 

CHEM.  1.  HNOa.  Instantly  blackens  with  vigorous  effervescence;  rubs  to  light 
gray  coating.  2.  KCN  -  .  3.  HCl.  Slowly  darkens,  persistent,  and  dissolves. 
4.  Aq.  Reg.  Rapidly  blackens  with  effervescence;  dissolved  deeply.  5.  FeClj. 
Instantly  attacked,  differentially,  some  grains  hardly  touched,  others  dark- 
ened. 6.  KOH  -  . 
DIFF.  Col.  Chem.  1,  2. 

NOTE.  The  friction  of  rubbing  lightly  on  a  rouge  block  tarnishes  bismuth 
yellow.  This  yellow  is  very  distinctive  for  bismuth.  If  dried  without 
rubbing,  the  true  color  is  preserved. 

DYSCRASITE  AgsSb,  Ag9Sb,  etc. 

COL.  White.  With  galena,  pale  creamy  white;  with  silver,  pale  creamy  white; 
with  argentite,  white. 

HARD.     Low.  SURF.     Smooth.  H.  3.5-4  <C  niccolite. 

CHEM.  1.  HNOs.  Tarnishes  and  rapidly  develops  "  felted  "  acicular  structure  or 
coarser  intergrowth,  differentially  etched.  2.  KCN.  Develops  brownish  needles 
or  patches  rather  slowly,  and  faint,  on  white  ground.  3.  HCl.  About  the  same  as 
HNO3,  not  so  good.  4.  HCl  cone.  Same  as  HCl.  5.  Aq.  Reg.  Sometimes  with 
effervescence.  Instantly  iridescent,  then  pale  brownish,  rubs  off  to  brilliant 
iridescent  colors.  6.  FeCl3.  Instantly  brilliant  iridescent.  Differential  tarnish, 
part  turned  yellowish,  part  with  needles  brilliant,  persistent.  7.  KOH  -  .  8. 
(NH4)2SX.  Quickly  develops  "  felted  "  structure,  in  bright  brown,  then  darkens 
to  very  dark  green,  which  rubs  off  easily,  showing  structure  again.  9.  NHiOH 

DIFF.     Chem.  1,  2. 
TAPALPAITE.  3  Ag2(S,Te).Bi2(S,  Te)3  ?  Mixture? 


Jj 

^ 


COL.  Creamy  white.  (Shows  intergrowth  of  gray  and  creamy  white.  Only 
creamy  part  of  specimen  is  considered  here.  For  gray  'part,  see  page  107.) 
With  galena,  creamy  white;  with  silver,  slightly  creamier  white. 

HARD.     Low.  SURF.     Smooth.  (/) 

CHEM.     1.  HNO3.    Instantly  blackens  with  effervescence;  coated  with  white  (?); 

fumes  tarnish.     Rubs  to  blackened,  etched  surface.     2.  KCN—  .     3.  HCl.  m  fj 

Faint  brown,  fumes  tarnish  faintly.    Rubs  clean.    4.  Aq.  Reg.    Effervesces  and  rt  . 

slowly  turns  grayish.     Fumes  tarnish  slightly;    rubs  clean  easily.     5.  FeCla.  V  /* 

Instantly  iridescent,  darkening.     Rubs  to  gray,  rough.     6.  KOH  -  .  TT.          A 

DIFF.     Chem.  1,2,3. 


CHILENITE                                                        ga  ^ 

COL.     Creamy  white.     With  galena,  deep  creamy  white;    with  silver,  slightly  Q)  V 

creamier.  yj  • 

HARD.     Low.                                SURF.     Smooth.  »T*  T 

CHEM.     1.  HNOs.    Instantly  effervesces  and  blackens.    Dissolves;  rubs  clean,  JJ  ^                  ~.~ 

giving  very  rough  surface.     2.  KCN.    Instantly  yellowish  brown;  rubs  clean  9  -                  \/4 


.       .  .  - 

easily.    3.  HCl.    Instantly  iridescent,  then  brown,  shows  roughened  surface.  fj    2  C/) 

Rubs  to  persistent  iridescent.     4.  Aq.  Reg.    Like  HCl,  but  more  vigorous.    5.  QJ 

*•+ 

^t 

Q; 


. 

FeCl3.    Instantly  brilliant,  then  darker,  iridescent.    Rubs  to  persistent  irides- 

cent  gray.     6.  KOH  -  .  ^  ^t 

DIFF.     Chem.  2,  3. 


TEALLITE.     See  page  106. 

125 


SH 

I 

1 

3! 


S 
I 


WHITE 

HARDNESS  Low 
CREAMY  WHITE 
DARKER  THAN  SILVER 
HNOs  NEQ. 


UNKNOWN  (creamy,  from  Butte,  Mont.)  ? 

COL.     Creamy   white.     With   galena,   faintly   creamy   white;    with 

silver,  faintly  grayish  white. 

HARD.     Low.  SURF.     Smooth.  H.  =  bn. 

CHEM.    1.  HNO3  -  .    2.  KCN.    Slowly  pale  purple  tarnish;  rubs  clean 
easily.     3.  HC1  -  .     4.  Aq.  Reg.  -  .     5.  FeCb  -  .     6.  KOH  -  . 
DIPT.     Chem.  1,  2. 

NOTE.     Probably  carries  bismuth. 


8 

ft  SULVANITE        See  page  72. 

I 

.  CHALMERSITE        See  page  72. 

^-  BERTHIERITE        See  page  103. 

I 

GOLD  (var.  electrum)         See  page  62. 


S:  126 

I 


GRAY 


I 


(0 


I 


UJ 

z 

Q 

c* 


127 


s 

I 


WHITE 

HARDNESS  Low 
GALENA  WHITE 
PURE  WHITE 
HC1 


PbTe 

With  galena,  pure  white; 


with  silver,  whiter  than 


I 


ALTAITE 

COL.     White, 
silver. 

HARD.     Low.  SURF.     Smooth.  H.  3  +. 

CHEM.     1.  HNOa.    Quickly  brown  with  effervescence,  develops  little 
crystallites  ?  (or  crosses  and  treelike  forms)  in  it.     Rubs  to  gray, 

showing  etch  figures  better.    2.  KCN .     3.  HC1.     Quickly  bright 

iridescent;  rubs  to  grayish  brown,  develops  cracking,  and  leaves 
some  uncolored  patches.  4.  Aq.  Reg.  Instantly  bright  iridescent 
tarnish;  dries  pale,  and  rubs  clean  readily.  5.  FeCls.  Instantly 
bright  brown  iridescent,  persistent;  rubs  to  gray  and  rough.  6. 

KpH .     7.  NaOH .     8.  (NHOaSx .     9.  Iodine,    Tarnishes 

bright  yellowish,  rubs  clean  easily. 

DIFF.     Chem.  1. 


CLAUSTHALITE  PbSe 

COL.  White.  With  galena,  pure  white;  with  silver,  white  with  faint 
bluish  cast. 

HARD.     Low.  SURF.     Smooth.  H.  2.5-3. 

CHEM.  1.  HNO3.  Brick  red  coating  forms  instantly,  which  rubs  off, 

leaving  a  grayish  brown  stain.  2.  KCN .  3.  HC1.  Slowly  darkens, 

brownish,  rubs  clean.  4.  HC1  cone.  Same.  5.  Aq.  Reg.  Instantly 
bright  iridescent;  rubs  to  greenish  gray.  6.  FeCls.  Slowly  darkens, 
coated  with  mixed  blue  and  yellow,  yellowish  by  oblique  light;  per- 
sistent. 7.  KOH . 

DIFF.     Chem.  1. 


H 

I 

I 

Si 


NAUMANNITE  (Ag2Pb)  Se 

COL.  White.  With  galena,  pure  white;  with  silver,  white  with 
bluish  cast. 

HARD.     Low.  SURF.     Smooth.  H.  2.5. 

CHEM.  1.  HNOs.  Instantly  blackens  with  effervescence;  leaves  very 
rough  surface.  2.  KCN .  3.  HC1.  Slowly  bright  brown  irides- 
cent. 4.  Aq.  Reg.  Instantly  iridescent,  and  blackens  with  efferves- 
cence; rubs  to  gray.  5.  FeCU.  Slowly  bright  brown;  rubs  clean 
easily  and  leaves  very  shallow  solution  pit.  6.  KOH . 

DIFF.     Chem.  1. 


a: 

g 


128 


GRAY 


I 


! 


uu 
z 

Q 


WHITE 

HARDNESS  Low 
GALENA  WHITE 
PURE  WHITE 
HC1  NEQ. 


^  GALENOBISMUTITE  PbBi2S4 

W  COL.     White.     Mixture   (?)   of  silvery  white  and  faintly  yellowish 

white,  somewhat  harder.     With  galena,  mixture  of  slightly  different 
shades  of  creamy  white;   with  silver,  practically  white. 
.  Occ.     As  blades  or  plates. 

bO  HARD.     Low.  SURF.     Smooth.  H.  3-4. 

^  CHEM.     1.  HNOs.     Instantly  bright  brown,  then  black.     Washes  off  to 

i^  show  whiter  portion  black,  and    grayer  part  coated  with  orange 

yellow.     White    more    dissolved    than    other.      2.    KCN .     3. 

?*  HC1 .     4.  Aq.  Reg. .     5.  FeCls .     6.  KOH . 

|j)  DIFF.     Chem.  1,  4. 

Cq  BISMUTHINITE  Bi2S3 

^«  COL.     White.     With  galena,  whiter,  and  less  bluish;  with  silver,  pale 

J*2  grayish  white.     Shows  different  colors  along  and  across  the  cleavage. 

!^J  Occ.     As  blades  and  plates. 

^  HARD.     Low.  SURF.     Smooth.  H.  2. 

^  CHEM.     1.  HNOs.    Blackens  immediately,  leaving  a  rough  solution  sur- 

face.     2.  KCN .    3.  HC1 .    4.  HC1  cone.     Tarnishes  iridescent. 

^                                                    5.  Aq.  Reg.    Eff ervesces  slightly  and  slowly  turns  brown;  rubs  clean f 
^  showing  roughened  surface.     6.  FeCls .     7.  KOH .     8.  NaOH 

.     9.  (NH)2Sx .     10.  NH4OH . 

^  DIFF.    Chem.  1,  5. 

i 

O  EUCAIRITE  Cu2Se.Ag2Se 

COL.     White.     With  galena,  bright  white,  makes  galena  look  yellow- 
ish;  with  silver,  bright  white. 

HARD.     Low.                       SURF.     Smooth.  H.  2.5. 
CHEM.   1.  HNOs.   Unchanged  for  a  moment,  then  rapidly  tarnished  and 
blackened.     Coated  with  orange  yellow  or  reddish.     Rubs  to  green- 
ish gray.     2.  KCN .     3.  HC1 .      4.  Aq.  Reg.    Instantly  effer- 
vesces, then  stops,  and  turns  slowly  faint  brown.     Rubs  clean  easily. 
U4                                                     Places  where  bubbles  started  marked  by  white  coating.     5.  FeCl3. 

5^  Slowly  very  faint  brown.     6.  KOH . 

J>  DIFF.     Chem.  1,  4,  5. 

JC  NOTE.     Gives  off  selenium  odor  when  ground  on  the  coarse  wheel. 

>  TELLURIUM  Te 

(/)  COL.     White.     With  galena,  almost  pure  white;   with  silver,  practi- 

i*4  cally  pure  white;  with  altaite,  very  pale  creamy  white. 

HARD.     Low.          SURF.     Semi-metallic,  smooth.  H.  2-2.5. 

CHEM.    1.  HNOs.    Instantly  effervesces  and  blackens;   rubs  to  dark 

J2  gray,  rough  surface.     2.  KCN .     3.  HC1; — .     4.  Aq.  Reg.     Effer- 

^  vesces  and  turns  brown,  then  black,  forming  white  coating.     Rubs 

to  rough  and  gray.    5.  FeCls.    Slowly  iridescent,  brilliant.    Persis- 
tent;  shows  solution  surface.     6.  KOH . 

DIFF.    Chem.  1,  6. 

UNKNOWN  (white,  from  Bisbee,  Ariz.)        ? 
COL.     White.     With  galena,  pure  white. 
HARD.     Low.  SURF.     Smooth.  H.  =  gn. 

CHEM.    1.  HNO3 .    2.  KCN.    Very  slowly  brown,  then  iridescent; 

rubs  clean  easily.     3.  HC1 .     4.  Aq.  Reg.    Instantly  iridescent, 

JS  then  black;|  rubs  to  roughened  black  surface.    5.  FeCls.    Quickly  iri- 

5S  descent  and  blackens;   rubs  clean,  showing  roughened  surface.     6. 

j^  KOH.   Rather  quickly  iridescent  then  black,  persistent. 

DIFF.     Chem.  6. 

5 

5  130 

1 


GRAY 


LEHRBACHITE  PbSe  -f  HgSe 

COL.     Pure  white.     With  gajena,  pure  white. 

HARD.     Low.  SURF.     Smooth. 

CHEM.  1.  HNO3 .  2.  KCN .  3.  HC1 .  4.  Aq.  Reg. .  5. 

FeCls .  (Possibly  FeCls  browns  slightly,  but  observations  were 

made  in  presence  of  soluble  gangue,  so  reactions  may  be  modified.) 
6.  KOH . 

DIFF.     Chem.  1. 


BERZELIANITE  Cu2Se 

COL.     Pure  white.     With  galena,  pure  white. 

HARD.     Low.  SURF.     Smooth. 

CHEM.  1.  HNOa.  Untouched  an  instant,  then  quickly  bright  irides- 
cent, with  a  little  reddish  coating.  Rubs  to  greenish  gray  tarnish. 

2.  KCN .  3.  HC1 .  4.  Aq.  Reg.  Quickly  brown,  then  bright 

iridescent.  Rubs  to  pale  gray.  5.  FeCla.  Rather  soon  light  brown 
(seen  on  rinsing  off  reagent).  Rubs  clean  easily.  6.  KOH . 

DIFF.     Chem.  1,  4,  5. 


ANTIMONIAL  BISMUTHINITE       Bi2(S,Sb)3 

COL.     White.     With  galena,  pure  white,  or  with  a  faint  creamy  tinge. 
Occ.     Plates,  usually  thin,  or  blades,  appearing  as  needles  in  the 

section. 

HARD.     Low.  SURF.     Smooth.  H.<C  en  =  gn. 

CHEM.    1.  HKOs.    Slowly  tarnishes,  then  blackens,  finally  thinly  coated 

with  white.     Rubs  off  gray,  and  rough.     2.  KCN .     3.  HC1 . 

4.  HC1  cone. .     5.  Aq.  Reg.    Quickly  bright  brown,  then  black. 

Rubs  to  persistent  rough,  dark  surface,  showing  much  solution.     6. 

FeCk .     7.  KOH . 

DIFF.     Occ.     Chem.  1,  5. 


MATILDITE         See  page  140. 


*  * 

<0  £ 

:    s 

« 

s 

D 


131 


fi 

(0 

(0 


S  WHITE 

S^«  HARDNESS  Low 

GALENA  WHITE 
SAME  AS  GALENA  OB  DABKEB 

^  HN03 

KCN  NEQ. 

<  HC1 

3 


QQ 


I 


FeCls  Neg. 


GEOCRONITE 

COL.     White.     With  galena,  very  slightly  creamy,  almost  the  same; 

with  silver,  faintly  bluish  white. 

HARD.     Low.  SURF.     Smooth.       -  H.  2.5. 

CHEM.    1.  HNOs.   Quickly  tarnishes  and  blackens,  with  white  coating; 

rubs  to  iridescent  gray,  showing  little  "crystallites."     2.  KCN . 

3.  HC1.    Very  slowly  faint  brown.    4.  HC1  cone.    Instantly  bright 

brown.     5.    Aq.   Reg.     Rapidly   tarnishes   brilliant   iridescent.     6. 

FeCls .     7.  KOH .     8.  NaOH . 

DIFF.     Chem.  1,  2,  5,  6. 


rr> 


^,  MENEGHINITE 

]2J  COL.     White.     With  galena,  faintly  grayish  (or  creamy  white)  very 

close. 
HARD.     Low.  SURF.     Smooth.  H.  =  gn. 

1^  CHEM.    1.  HNOs.    Untouched  a  moment,  then  very  rapidly  blackens. 

(V  Appears  gray  by  oblique  light.     Rubs  to  gray  surface,   showing 

smooth  white  crystallites,  like  geocronite.      2.   KCN.  -     3.  HC1. 

>•*  Slowly  gray,  some  grains  more  than  others.     Fumes  tarnish  a  bright 

ring.     Rubs  off,  leaving  a  shallow,  grayish  pit.     4.  Aq.  Reg.    Turns 
rather  slowly  iridescent.     Fumes  tarnish.     Rubs  to  persistent  iri- 
descent.    5.   FeCls  -  .     6.    KOH.     Very   slowly   colored   blue   or 
reddish. 
DIFF.     Chem.  1,5,7. 

SEMSEYITE  Pb7Sb6Si« 

COL.     White.     With  galena,  very  slightly  grayish   (creamy)   white, 
^j  almost  same.     Two  faintly  different  colors  observed,  apparently  due 

to  orientation. 
^  HARD.     Low.  SURF.     Smooth. 

CHEM.    1.  HNOs.    After  a  moment  bright  iridescent,  quickly  blacken- 

j^  ing;    coated  thinly  with  white.     Rubs  off  to  show  persistent  gray, 

j<  slightly  roughened  surface.    2.  KCN  -  .    3.  HC1.    Slowly  very  faint 

brown.     Fumes  tarnish  narrow  ring,  brightly.     Rubs  clean  easily. 

^j  4.  Aq.  Reg.    Instantly  iridescent,  then  blackens,  with  effervescence. 

J  Fumes  tarnish  brilliant.     Rubs  to  faint  gray,  roughened  surface. 

5.  FeCla  -  .     6.  KOH  -  . 
DIFF.     Chem.  1. 


< 
I 

ZINKENITE         See  page  111. 
PLAGIONITE         See  page  135. 
JAMESOKITE        See  page  111. 


GRAY 


FeCL 


LILLIANITE  ,   Pb3Bi2S« 

COL.     White.     With  galena,  same.     Shows  cubic  cleavage  by  incip- 
ient alteration. 

HARD.     Low.  "SuRF.     Smooth.  H.  =  gn? 

CHEM.    1.  HNO3.    Instantly  iridescent.    Ru bs  clean  and  smooth  easily. 

2.  KCN .     3.  HC1.      Slowly  light  brown  (differential  action  on 

different  grains).     Fumes  tarnish  bright.     Rubs  off  rather  easily, 

smooth  and  clean.     4.  Aq.  Reg.    Instantly  dark  brown,  then  nearly 

black,  coated  with  white.     Fumes  tarnish  a  narrow  rim,   bright. 

Rubs  clean  and  smooth  easily.    5.  FeCls.     Slowly  bright  iridescent. 

Rubs  smooth  and  clean  easily.     6.  KOH . 

DIFF.     Surf.     Chem.  1. 

GALENA  PbS 

COL.     White.     With  silver,  bluish  white. 

HARD.     Low.     SURF.     Smooth,  but  usually  H.  2.5-2.75.  3C 

shows  triangularlpits. 
CHEM.    1.  HNOs.    Blackens  quickly  with  a  dark,  persistent  coating.    2. 

KCN .    3.  HC1.   Slowly  faint  brown.  4.  HC1  cone.  Quickly  brown, 

fumes  tarnish.    5.  Aq.  Reg.    Instantly  blackens.    6.  FeCls.    Bright, 

iridescent,  persistent.     7.  KOH .     8.  (NH4)2Sx .     9.  NH4OH 

DIFF.'    Surf.     Chem.  1. 

NOTE.  A  specimen  of  galena  from  Central  City,  Col.,  intergrown 
with  tellurides  and  native  tellurium,  with  HNOs  is  unchanged 
for  an  instant,  then  turned  dark  brown;  rubs  clean  to  show 
smooth  solution  pit,  cream  colored. 

Galena  with  intergrown  pure  white  or  creamy  minerals,  such 
as  selenides  or  tellurides  is  apt  to  appear  very  purple,  and  care 
must  be  taken  not  to  confuse  it  with  purple  "galena,"  which  is 
really  purplish,  as  is  shown  by  comparing  it  with  ordinary  galena. 

STEINMANNITE  PbS  (As,  Sb)  (var.  galena) 

COL.     White.     With  galena,  same. 

HARD.    Low.    SURF.    Smooth,  with  triangular  cleavage  pits.    H  =  gn? 
CHEM.     1.  HNOs.     Instantly  iridescent,  then  blackens  with  efferves- 
cence;   coated  with  white.      Rubs  to  gray  rough  surface.     2.  KCN 

.     3.  HC1.     Rather  quickly  blackens,  and  is  coated  with  white. 

Rubs  off  to  show  rough  gray  surface,  with  spots  which  rub  clean  and 

smooth.     4.   Aq.  Reg.      Instantly  iridescent,  then   black.     Coated 

thinly  with  white;    rubs  clean  easily  and  shows  slightly  roughened 

surface.    5.  FeCls.   Slowly  bright  iridescent.    Rubs  clean  and  smooth 

easily.     6.  KOH . 

DIFF.     Surf.     Chem.  1. 

TETRAD  YMITE  ?  Bi2(TeS)3 

COL.     White.     With  galena,  very  slightly  yellowish  or  grayish,  prac-  . 
tically  the  same;  with  silver,  pale,  decidedly  purplish  grayish  white; 

with  bismuthinite,  decidedly  purplish  gray.  £H               t% 

HARD.     Low.                       SURF.     Smooth.                                   H.  1.5-2.  {J              * 

CHEM.    1.  HNOs.   Rather  rapidly  deep  brown,  then  black  fumes  tarnish  M               ^ 

brownish.     Rubs  to  rough,  light  gray  surface.     2.   KCN .     3.  J2 

HC1.     Slowly  bright  brown;  rubs  to  uneven  pale  brown.     4.  HC1  ^ 

cone.    Quickly  brown,  then  iridescent.     5.  Aq.  Reg.    Slowly  brown,  ^ 

somewhat   persistent.    6.    FeCls.    Slowly    faint    brown,    persistent.  0 

Rubs  clean,   shows  solution  surface.     7.   KOH .     8.   (NH4)2Sx. 

Darkens  to  deep  grayish  brown,  rubs  clean.  <fl 


Rubs  clean,   shows  solution  surface.     7.   KOH .     8.   (NH4)2Sx.  C/) 

Darkens  to  deep  grayish  brown,  rubs  clean.  <fl  r/\ 

DIFF.     Surf.     Chem.  1,2.  fi 

NOTE.     Shows  galena  (?)   cleavage,  and  may  possibly  be  only  ^ 

galena  carrying  tellurium.     Intergrown  with  a  little  of  a  creamy  ~* 

mineral  which  might  be  the  true  tetradymite.  e*  Q 

*  I 

133  „ 

6 


WHITE 

HARDNESS  Low 

GALENA  WHITE 

SAME  AS  GALENA  OR  DAI 

HNOa 

KCN  NEQ. 

HQ  NBQ. 

FeCl  NEQ. 

No  Eff.  HNOs 
NAGYAGITE  Au2Pb10Sb2Te6S15  (Hintze) 

COL.     White.     With  galena,  very  pale  grayish  white;  nearly  same;  with  silver, 

pale  bluish  grayish  white. 

HARD.     Low.  SURF.     Smooth.  H.  1-1.5. 

CHEM.     1.  HNO3.    After  a  short  time  suddenly  iridescent,  bright;  rubs  to  dark 

gray.     2.  KCN .    3.  HC1 .    4.  Aq.  Reg.    Quickly  iridescent,  then  black. 

5.  FeCl3 — .     6.  KOH . 

DIFF.     Chem.  1. 

FREIESLEBENITE  (PbAg^Sb^Sn 

COL.     White.     With  galena,  pale  creamy  white;    with  silver,  pale  (brownish) 

cream. 

HARD.     Low.                               SURF.     Smooth.  H.  2-f. 

CHEM.     1.  HNO3.    Blackened  and  roughened.    2.  KCN — .    3.  HC1 .     4.  Aq. 

Reg.    Instantly  effervesces  then  turns  bright  brown  iridescent,  rubs  clean  easily. 

5.  FeCl3 .    6.  KOH .    7.  NaOH .    8. 

DIFF.    Chem.  1,  6. 

GUITERMANITE  Pb3As2S6 

COL.     White.     With  galena,  very  close,  slightly  grayish  (?). 

HARD.     Low.  SURF.     Smooth. 

CHEM.     1.  HNO.    Instantly  bright  iridescent.     Rubs  clean,  leaving  roughened 

surface.     2.  KCN .     3.  HC1 .     4.  Aq.  Reg.     Instantly  iridescent,  with 

effervescence;   then  darkens.     Rubs  to  gray  roughened  surface.      5  FeCl . 

6.  KOH      . 
DIFF.     Chem.  1,  4. 

BEEGERITE  Pb,,Bi2S9 

COL.     White.     With  galena,  very  pale  creamy  white;    with  silver,  decidedly 

grayish  white. 

HARD.     Low.  SURF.     Smooth.  H.  <  cp. 

CHEM.     1.    HNO3.     Parts  instantly,  parts  slowly,  iridescent.     Fumes  tarnish 

brown.     Rubs  easily  to  pale  gray.     2.  KCN .     3.  HC1 .     4.  Aq.  Reg. 

Instantly  effervesces  slowly,  and  turns  bright  iridescent,  then  black.     Fumea 
tarnish   bright.     Parts   coated   with   white.     Rubs   to   iridescent   gray.     5. 

UJ  FeCl3 .     6.  KOH . 

Kj  DIFF.     Chem.  1,  4. 

JORDANITE  ?  PbiAszS:      ? 

COL.     White.     With  galena,  very  pale  grayish  white,  very  close;  with  tetrahe- 

drite,  practically  white. 

HARD.     Low.                              SURF.     Smooth.                                            H.  <  si. 
CHEM.    1.  HNO3.    Untouched  a  moment,  then  slowly  light  gray.    Rubs  very  pale 
gray,  slightly  rough.    2.  KCN .    3.  HC1 .     4.  Aq.  Reg.    Instantly  irides- 
cent, effervesces  and  blackens.    Rubs  to  gray  roughened  surface.     5.  FeCl . 

6.  KOH . 

£j\  DIFF.     Chem.  1. 

L^  ANDORITE                                                      Pb2Ag2Sb6S9 

JL  COL.     White.     With  galena,  very  pale  (creamy)  grayish  white;   with  silver,  dull 

SN,  grayish  white;  with  tetrahedrite,  much  lighter,  grayish  white. 

M^  HARD.     Low.                              SURF.     Smooth.                                      H.  =  3-3.5? 

J^.  CHEM.     1.  HNO3.    Rather  slowly  iridescent,  rubs  clean  easily.     2.  KCN .     3. 

^  HC1 .    4.  Aq.  Reg.    Slowly  brown,  then  brilliant  iridescent,  with  increasing 

effervescence.     Fumes  tarnish  brilliant  ring  quickly.     White  coating  formed. 

S»«  Rubs  off  to  show  deeply  etched  surface.    5.  FeCl3 .    6.  KOH.    Slowly  pale 

*^<  brown,  darkening  to  bluish  iridescent.     Rubs  clean  easily. 

C/}  DIFF.     Chem.  4,  6. 

^J  EPIBOULANGERITE                                     Pb3Sb2S8 

^»  COL.     Galena  white.     With  galena,  practically  the  same.     Faintly  greenish  gray. 

i^  HARD.     Low.                              SURF.     Smooth.                                                      H. 

^*  CHEM.    1.  HNO3.    Untouched  a  moment,  then  blackens,  and  is  coated  with  white. 

**N  Rubs  off  to  show  gray  surface  studded  with  little  white  crystals  which  have 

„  p^»  rubbed  clean.    2.  KCN .     3.  HC1 .     Fumes  tarnish  slightly.    4.  Aq.  Reg. 

fS  y                    Instantly  effervesces  and  blackens.     Fumes  tarnish  bright  iridescent.     Rubs  to 

£:  !^J  gray,  etched  surface.     5.  FeCl3 .     6.  KOH . 

^  DIFF.     Chem.  1. 

Kj  UNKNOWN  (near  andorite)  ? 

COL.     White.     With  galena,  very  pale  (greenish)  grayish  white,  rather  close. 
HARD.     Low.  SURF.     Smooth.  H.  gn. 

CHEM.     1.  HNO3.     Very  slowly  brown  and  iridescent;   rubs  to  faint  gray.     2. 

KCN .    3.  HC1 .    4.  HC1  cone. .    Fumes  tarnish  light  brown.    5.  Aq. 

IJj  Reg.    Instantly  effervesces  and  turns  iridescent,  darkens,  with  little  or  no  white 

l^  coating.     Fumes  tarnish  brilliant  iridescent;   rubs  to  gray  roughened  surface, 

^  fumes  rub  clean.     6.  KOH .     7.  FeCl3 . 

s^J  DIFF.     Chem.  6. 

t^  NOTE.     Very  close  to  andorite  in  properties. 

£  BISMUTHINITE         See  page  130. 

LENGENBACHITE         See  page  141. 

*^  BAUMHAUERITE         See  page  108. 

£j  JAMESONITE        See  page  111. 

<  134 


GRAY 


Eff.  HNOs 


BOULANGERITE  ~Pb3Sb2S« 

COL.     White.     With  galena,  very  pale  grayish  white,  with  silver,  very 

pale  bluish  grayish  white. 

HARD.     Low.                     SURF.     Smooth.  H.  2.5-3. 

CHEM.     1.  HNOs.    Rapidly  blackens  with  effervescence.    2.  KCN . 

3.  HC1 .    4.  Aq.  Reg.    Same  as  HNO3  but  slower.    5.  FeCl* . 

6.  KOH .     7.  NaOH .    8.  (NH4)2SX .  ^ 

DIFF.     Chem.  1. 

DOGNACSKAITE  Bi,Cu,S  ?  £j 

COL.     White.     With  galena,  pale  creamy  white;    with  silver,  pale  ^J 

grayish  white.     Also  shows  some  intergrowth  of  a  bluish  mineral, 

same  hardness. 

HARD.     Low.  SURF.     Smooth. 

CHEM.     1.  HNOs.     Instantly  effervesces  and  tarnishes  iridescent,  then 

blackens.     Coated  with  pale  yellowish  white.     Fumes  tarnish,  rubs 

to  rough  black.     2.  KCN .     3.  HC1 .     4.  Aq.  Reg.     Instantly 

effervesces    and    tarnishes    brown.     Fumes    tarnish.     Rubs    clean 

easily,    showing   slight   solution   pits   where   bubbles   started.     5. 

FeCls .     6.  KOH . 

DIFF.     Chem.  1,  6. 

HORSFORDITE  Cu6Sb  ? 

COL.  White.  With  galena,  very  pale  creamy,  almost  same;  with 
silver,  pale  bluish  or  grayish  white. 

HARD.     Low.  SURF.     Smooth.  H.  4-5. 

CHEM.  1.  HNOs.  Instantly  blackens  with  slight  effervescence;  rubs  to 
light  gray  iridescent.  2.  KCN .  3.  HC1 .  4.  Aq.  Reg.  In- 
stantly etches;  part  brown,  part  little  changed;  rubs  to  pale  gray. 

Fumes  tarnish  bright.  5.  FeCls .  6.  KOH.  Slowly  faint  brownish 

and  bluish;  rubs  faint. 

DIFF.     Chem.  1,  6. 

PLAGIONITE  PbsSbsSn 

COL.     White.     With  galena,  very  pale  grayish  white,  very  near. 

HARD.     Low.  SURF.     Smooth. 

CHEM.    1.  HNOs.    Untouched  a  moment,  then  quickly  dark  iridescent, 

with  effervescence;    finally  black.     Rubs  to  persistent  gray.     2. 

KCN .  (Or  very  slowly  faint  brown?).  3.  HC1 .  Fumes  tarnish 

bright.     4.    Aq,  Reg.     Instantly  effervesces  and  tarnishes  bright. 

Fumes  tarnish  brilliant.     Rubs  clean  easily.    5.  FeCls .     6.  KOH. 

Slowly  brown,  then  purple,  then  blue,  iridescent.     Washes  to  pale  (• 

blue.     Rubs  clean  very  easily.  ^  9) 

DIFF.     Chem.  1,  6  " 

a          £ 

:    s 

CHIVIATITE         See  page  120. 

2 


i 


135  0) 

i 


» 


Vl  WHITE 

|S<  HARDNESS  Low 

^  GALENA  WHITE 

"^  SAME  AS  GALENA  OB  DARKER 

^  HNO3 

KCN  NEQ. 
<  HC1  NEQ. 

FeCU 


ARSENIC  AS 

COL.     White.     With  galena,  faintly  creamy  white,  almost  the  same; 

with  silver,  very  close,  with  a  suggestion  of  gray. 
HARD.     Low.  SURF.     Smooth.  H.  3.5. 

CHEM.    1.  HNOs.    Instantly  darkens,  through  brown  to  black,  with  slow 

effervescence;    rubs  to  bluish  gray.     2.  KCN .      3.  HC1 .     4. 

Aq.  Reg.    Turns  slowly  brown  with  effervescence;  rubs  off  to  show 
fT>  uneven    solution  surface.     5.    FeCls.     Quickly    darkens,  brownish, 

WJ  persistent.     6.  KOH . 

^«  DIFF.     Chem.  5. 

J^j  NOTE.     Gives  off  arsenic  odor  when  ground  on  the  coarse  wheel. 

UNKNOWN     ("ALLOKLAS")  ? 

^,  COL.     White.     With  galena,  pale  creamy  white,  rather  close. 

«_  HARD.     Low.  SURF.     Smooth.  H.  <  cp. 

^  CHEM.     1.  HNOs.     Instantly  effervesces  and  blackens;  coated  with 

^  white.     Rubs  to  black  etched  surface.     2.  KCN .      3.  HC1 . 

Q>  4.   Aq.  Reg.     Instantly  effervesces  and  tarnishes  brown.     Fumes 

Z£j  tarnish  bright  brown.     Rubs  off  to  show  grayish  etched  surface.     5. 

p5  FeCls.     Slowly  very  faint  brown.     6.  KOH . 

O  DIFF.     Chem.  1,  5. 

NOTE.     This  is  a  specimen  labelled  alloklas,  but  not  agreeing  with 
the  descriptions  of  alloclasite. 

REZBANYITE  Pb4BiioSi9 

COL.     White.     With  galena,  very  pale  grayish  white  (two  faintly  dif- 
£r>  ferent  shades,  probably  due  to  different  orientation). 

HARD.     Low.  SURF.     Smooth.  H.  =  2.5-3. 

^J  CHEM.     1.  HNOs.    Instantly  iridescent;  fumes  tarnish  bright.    Etched 

s5J  differentially,  some  grains  more  rapidly  than  others.     Rubs  to  pale 

^  gray,  etched  surface.     2.  KCN .     3.  HC1 .     4.  Aq.  Reg.     In- 

^  stantly  effervesces  and  tarnishes  iridescent.     Fumes  tarnish  bright. 

Rubs  to  pale  gray  etched  surface.     5.  FeCls.     Slowly  faint  brown. 

^  6.  KOH . 

^  DIFF.     Chem.  1,  5. 

£ 

PLENARGYRITE  (hard)  AgBiS?  (mixture) 

«ML  COL.     Shows  intergrowth  of  creamy  (hard)  and  bluish  (soft)  whites. 

"^  With  galena,  very  pale  creamy  (?)  white;  with  silver,  grayish  white. 

w  c*-  HARD.     Low.  SURF.     Smooth.  H.  =  2.5? 

O  sj  CHEM.    1.  HNOs.    Slowly  iridescent.    Rubs  clean  easily.     2.  KCN . 

J^  '"S  3.  HC1 .     4.  Aq.  Reg.    Quickly  bright  iridescent,  then  darker. 

S  Fumes  brilliant  iridescent.     Rubs  black  and  rough,  showing  deep 

*N  1        solution.    5.   FeCla.    Very   slowly   brown.     Rubs   clean   easily.    6. 

KOH . 

DIFF.     Chem.  1,  4. 

NOTE.     Very  like  schapbachite  in  general  appearance. 


I 
I 

136 


GRAY 


SCHAPBACHITE  (hard)  PbAgsBisSs  (mixture) 

COL.  White.  Mixture  of  creamy  (?)  (harder)  and  bluish  (softer) 
whites.  With  galena,  pale  creamy  white.  With  silver,  grayish 
white.  bo 

HABD.     Low.  SURF.     Smooth.  H.  <  cp. 

CHEM.    1.  HNOs.    Slowly  brown;  rubs  clean.    2.  KCN .    3.  HC1 .  JZj 

4.  Aq.  Reg.     Slowly  pale  brown,  finally  dark  (like  HNO3).     Rubs 
clean.    5.  FeCl3.    Very  slowly  pale  brown.    Rubs  clean.    6.  KOH . 

DIFF.     Chem.  1,4. 

NOTE.     Very  like  plenargyrite  in  general  appearance. 


PETZITE  (AgAu)2Te 

COL.  White.  With  galena,  very  pale  grayish  brownish  white  (nearly 
the  same  as  hessite  ?). 

HARD.     Low.  SURF.     Smooth.  H.  2.5-3  <  galena. 

CHEM.  1.  HNOs.  Instantly  effervesces,  then  dark  brown.  Rubs  clean, 

showing  roughly  etched  surface.  2.  KCN .  3.  HC1 .  4. 

Aq.  Reg.  Instantly  brilliant  iridescent,  with  effervescence.  Fumes 
tarnish  brilliant.  Rubs  clean  easily.  5.  FeCls.  Quickly  iridescent, 
deepening  rapidly.  Rubs  clean  easily.  6.  KOH . 

DIFF.    Chem.  5. 


i 

i  1 

r*  Z 

<U  ><*s 

0        g 

s      I 

137  q, 

m 


B 

>J5  WHITE 

JS  HARDNESS  Low 

^  GALENA  WHITE 

**•  SAME  AS  GALENA  OB  DARKER 

HN03 
S 

GQ 


1 
I 


KERMESITE  Sb2S2O 

COL.     White.     With  galena,  slightly  darker,  almost  same;  with  silver, 

pale  bluish  white,  very  nearly  same.     Red  transparent  by  oblique 

light. 

HARD.     Low.  SURF.     Smooth.  H.  1-1.5. 

CHEM.    1.  HNO3.    Quickly  light  brown,  persistent.    2.  KCN.    Slowly 

darkens,  slightly,  and  rubs  to  lighter  brown.     3.  HC1  -  .     4.  Aq. 

Reg.    Effervesces  vigorously,  and  darkens  slightly.    5.  FeCla  -  .    6. 

KOH.     Instantly  iridescent,  then  coated  with  bright  yellow,  which 

rubs  off  easily. 
DIFF.     Col.     Chem.  4,  6. 


STIBNITE  Sb2S3 

COL.     White.     With  galena,  very  faintly  creamy,  with  silver,  faint 

grayish  white.     Differently  oriented  sections  vary  slightly  in  color. 
HARD.     Low.  SURF.     Smooth.  H.  2. 

CHEM.    1.  HNOs.   Quickly  darkens,  at  last  dark  brown.  2.  KCN.   Dis- 

solves  and  roughens  surface,  but  does  not  change  color.     3.  HC1  -  . 

4.  Aq.  Reg.    Blackens  rapidly  with  effervescence.    5.  FeCls  -  .    6. 

KOH.  Quickly  coated  with  bright  orange  yellow,  soon  turning  reddish 

brown.     Washes  off  easily,  leaving  rough  surface.     7.  NaOH  -  . 

8.  NH4OH  -  . 
DIFF.     Col.     Chem.  4,  6. 


HESSITE  Ag2Te 

COL.  White.  With  galena,  very  slightly  creamy,  almost  the  same; 
with  silver,  distinctly  bluish  gray. 

HARD.     Low.  SURF.     Smooth.  H.  =  2-3  <  gold. 

CHEM.  1.  HNOa.  Instantly  iridescent,  then  darkens  to  dark  brown. 
Rubs  clean,  leaving  a  roughened  surface.  2.  KCN.  Slowly  blackens 
and  dissolves,  giving  a  very  rough  surface.  3.  HC1  -  ?  4.  Aq.  Reg. 
Instantly  brilliant  iridescent  with  effervescence.  Fumes  tarnish 
brilliant.  Rubs  clean  easily.  6.  FeCla.  Instantly  iridescent.  Rubs 
clean  easily.  6.  KOH  -  . 

DIFF.     Chem.  5  (1),  6. 


I 

GUEJARITE         See  page  103. 

03 

«  BROGNIARDITE         See  page  110. 


2  •» 

i 


GRAY 


3 

» 

1 
g 


139  ^ 

e 

(0 


8 

£5  WHITE 

C;  HARDNESS  Low 

^  GALENA  WHITE 

^  SAME  AS  GALENA  OK  DARKER 

HNO3  NEQ. 

^  KOH  NEQ. 


No  Eff.  Aq.  Reg. 

I 


JALPAITE  3  AgjS-CusS  ? 

COL.     White.     With  galena,  very  pale  creamy  gray,  almost  same; 

with  silver,  dull  grayish  white;  with  argentite,  pale  brownish  cream  ; 

with  tetrahedrite,  very  close,  almost  same  (?). 

HARD.     Low.  SURF.     Smooth.  H.  2-2.5. 

CHEM.     1.   HNO3  -  .     2.    HNO3   cone,  -  .    3.    KCN.    Very   slowly 

browned,  develops  scratches;  rubs  off  rather  easily.    4.  HC1.    Slowly 

effervesces  a  little,  solution  turns  green,  surface  is  roughened.     5. 

Aq.  Reg.      Instantly   iridescent,    deepens   rapidly,   persistent.    6. 

FeCl8—  .    7.  KOH  -  . 
DIFF.     Chem.  3,  5. 


MALTILDITE  AgBiS2 

COL.  White.  With  galena,  very  slightly  creamy  or  grayish  white, 
almost  same;  with  silver,  distinctly  grayish  white;  with  matildite 
(?)  from  Japan,  grayer,  less  creamy. 

HARD.     Low.  SURF.     Smooth.  H.  2.5? 

CHEM.  1.  HNO3  -  .  2.  KCN  -  .  3.  HC1  -  .  4.  HC1  cone.  -  . 
5.  Aq.  Reg.  Fumes  instantly  tarnish  brilliant  iridescent,  acid  same, 
less  quickly,  and  darker  finally.  Effervesces  slightly  (?).  Rubs 
easily  to  a  clean,  very  slightly  roughened  surface.  6.  FeCli  -  .  7. 
KOH  -  . 

DIFF.     Chem.  2,  5. 


^  UNKNOWN  (Tonopah)         See  page  114. 

I 
I 


140 


GRAY 


Eflf.  Aq.  Reg. 


SCHIRMERITE  ( 

COL.     White.     With  galena,  practically  the  same  (faintly  creamier). 

HARD.     Low.  SURF.     Smooth. 

CHEM.  1.  HNO3  -  .  2.  KCN  -  .  3.  HC1  -  .  4.  Aq.  Reg.  In- 
stantly iridescent,  then  blackens,  with  effervescence;  coated  with 
white.  Rubs  to  roughened  iridescent  surface.  5.  FeCls  -  .  6. 
KOH  -  . 

DIFF.     Col.     Chem.  4,  6. 


RATHITE  Pb(As,Sb),S  ? 

COL.     White.     With  galena,  very  pale  bluish  (grayish)  white. 

HARD.     Low.  SURF.     Smooth. 

CHEM.     1.  HNOs  -  .     2.  KCN  -  .     3.  HC1  -  .     4.  Aq.  Reg.     Effer- 

vesces quickly  and  turns  brown,  then  black;    thinly  coated  with 

white.     Rubs    to    rough    gray    surface.     5.    FeCls  -  .     6.    KOH. 

Rather  quickly  pale  brown,  then  pale  purple  and  blue  iridescent. 

Rubs  to  very  pale  purplish  color. 
DIFF.     Chem.  6. 

NOTE.     Same  chemical  properties  as  seligmannite,   but  looks 

bluish  instead  of  creamy. 


LENGENBACHITE  Pb6(AgCu)2As4S« 

COL.     White.     With  galena,  very  pale  grayish  white;    with  tetra- 

hedrite,  distinctly  whiter. 
HARD.     Low.  SURF.     Smooth. 

CHEM.     1.  HNOs  -  ?  (Edge  of  specimen  slowly  tarnished  iridescent, 

but  perhaps  due  to  sealing  wax  mount.)     2.  KCN  -  .      3.  HC1  -  . 

4.  Aq.  Reg.    Instantly  iridescent,  effervesces,  finally  blackens.    Rubs 

to  faintly  gray,  roughened  surface.     5.  FeCls  -  .     6.  KOH  -  . 
DIFF.     Chem.  4,  6. 


CINNABAR  HgS 

COL.  White.  With  galena,  pale  bluish  gray;  with  tetrahedrite,  dull 
grayish  white.  Transparent  brilliant  red  with  oblique  light. 

HARD.     Low.  SURF.     Smooth.  H.  2-2.5. 

CHEM.  1.  HNOs .  2.  KCN .  3.  HC1  cone, .  4.  Aq.  Reg. 

Effervesces  and  darkens,  iridescent.  Rubs  clean.  5.  FeCla .  6. 

KOH .  7.  (NH4)2Sx . 

DIFF.     Col. 


T3  O 

*  U  J 

0 
MATILDITE        See  page  140. 


OJ 

POLYBASITE        See  page  105.                                                                                                      J*  £ 

0  g 

BOURNONITE        See  page  92.                                                                                                       ^  J* 

141  C 

e 

(0 


6 

Hj  WHITE 

HARDNESS  Low 

^  GALENA  WHITE 

SAME  AS  GALENA  OR  DARKER 

^  HNOs  NEG. 

<  KOH 


a 


UJ 


bo  LIVINGSTONITE  HgSb4S7 

,*  COL.     White.     With  galena,  very  pale  grayish  white,  practically  the 

^  same;   with  silver,  very  pale  (bluish)  grayish  white.     Transparent 

w  deep  red  by  oblique  light. 

Q  HARD.     Low.  SURF.     Smooth.  H.  2. 

J^,  CHEM.    1.  HNO3  -  .    2.  HNOs  cone,  -  .    3.  KCN.    Very  slowly  faint 

Jrj  gray.     4.  HC1  -  .     5.  HC1  cone.  -  .     6.  Aq.  Reg.     Slowly  brown 

H«  with  effervescence.    7.  FeClj  -  .    8.  KOH.   Instantly  bright  yellow- 

ish brown. 
DIFF.     Col.     Chem.  5,  G,  8. 

STEPHANITE  Ag6SbS4 

COL.  White.  With  galena,  very  pale  grayish  white;  with  silver,  de- 
cidedly  bluish  gray;  with  argentine,  almost  pure  white;  with  tetra- 
hedrite,  bluish  gray;  with  proustite,  nearly  pure  white. 

HARD.     Low.  SURF.     Smooth.  H.  2-2.5. 

CHEM.  1.  HNOs  -  .  2.  KCN.  Immediately  darkens;  rubs  clean 
easily,  leaving  brown  edged  cracks.  3.  HC1  -  .  Fumes  very 
slowly  brown,  then  iridescent.  Rubs  off.  4.  HC1  cone,  -  .  Fumes 
tarnish  iridescent,  persistent,  forming  a  brilliant  ring  on  the  surface. 
5.  Aq.  Reg.  Instantly  iridescent,  blackens  with  slight  effervescence; 
rubs  to  dark  gray,  persistent,  and  shows  a  shallow  solution  pit. 
Fumes  tarnish  brighter  than  acid.  6.  FeCl3.  Slowly  develops  little 
black  flecks,  white  by  oblique  light.  Rubs  clean  easily.  7.  KOH. 
Rapidly  darkens  to  dark  brown;  rubs  clean  easily,  showing  solution 
surface.  8.  NaOH.  Same  as  KOH,  but  not  as  rapid.  9.  NH4OH  -  . 
10.  (NH4)2SV.  Slowly  brown,  rubs  clean  easily. 

DIFF.     Chem.  4,  7. 

SARTORITE  PbAs2S4 

COL.     White.     With  galena,  very  close. 

HARD.     Low.  SURF.     Smooth.  H.  =•  3? 

CHEM.     1.  HNOs  -  .     2.  KCN  -  .     3.  HC1  -  .      4.  Aq.  Reg.  -  ,  or 

very  slowly  faint  brownish  (doubtful,  because  of  mounting  wax)  .     5. 

FeCla  -  .     6.  KOH.     Quickly  faint  gray  (?),  slowly  etches,  de- 

veloping  structure.     Rinses  off  white  showing  etching  lines  (cleavage 

or  structure). 
DIFF.     Chem.  4,  6. 

DUFRENOYSITE  Pb2As2S6 

COL.     White.     With  galena,  very  close  (slightly  creamy  ?). 
HARD.     Low.  SURF.     Smooth.  H.  -  3? 

CHEM.    1.  HNO3  -  .    2.  KCN  -  .    Or  very  pale  tarnish,  slowly?    4. 
Aq.  Reg.    Quickly  brown,  then  iridescent,  effervesces  slowly.    Finally 
very  dark,  with  white  coating.     Rubs  to  blackened  rough  surface. 
*  5.  FeCl3  -  .     6.  KOH.     Rather  quickly  pale  iridescent,  developing 

C  different   grains;     then    gray.     Rubs   clean   easily,    showing   very 

>  strongly  differential  etching. 

J  DIFF.     Chem.  4,  6. 

NOTE.     Called  binnite  by  Heusser. 


BERTHIERITE         See  page  103. 
MIARGYRITE         See  page  115. 

142 


i 


GRAY 


I 

<o 
-0 

0 

(0 


s 

CO 


143 


GRAY 

HARDNESS  HIGH 
HC1  CONG. 


FRANKLINITE  FeZnMnO-(FeMn)sO» 

COL.     Gray.     With  galena,   dull   gray;    with  sphalerite,   distinctly 

lighter;  with  hematite,  grayer. 
HARD.     High.  SURF.     Shiny,  pitted.  H.  5.5-6.5. 

CHEM.     1.  HNO3 .     2.  KCN .     3.  HC1  cone, .    Acid  turns 

yellowish  brown,  slowly.     4.  Aq.  Reg.     Same  as  HC1   cone.     5. 

KOH .     6.  FeCla . 

DIFP.     Col.     Chem.  3. 

NOTE.     Very  hard  to  polish  free  from  pits. 

PSILOMELANE  H4MnOs  ? 

COL.     Gray.     With  sphalerite,  somewhat  lighter,  and  creamy;   with 

galena,  dull  gray. 

HARD.     High.                    SURF.     Smooth.  H.  5-6. 

CHEM.     1.  HNO3  cone, .     2.  HC1.     Quickly  darkens,  rubs  to  pale 

brown.     3.  HC1  cone.    Immediately  blackens  and  dissolves.     Acid 

turns  brown.     4.  Aq.  Reg.    Very  slowly  faint  brown,  persistent.     5. 

KOH .     6.  FeCls .     , 

DIFF.     Col.     Chem.  2,  3. 


MAGNETITE        See  page  91. 


i 


144 


GRAY 


(A 


2 

a 
c* 

E 


s 

Cft 
M 

tu 
a 

Q( 

145  E 


GRAY 

HARDNESS  HIGH 
HC1  CONG.  NEO. 


Aq.  Reg.  Neg. 


0?  CASSITERITE  SnOa 

^  COL.     Gray.     With  galena,  dull  brownish  (?)  gray;    with  sphalerite, 

slightly  lighter  (?)  and  creamy;    with  hematite,  dull  gray;    with 

^J  magnetite,  dull  gray;    sometimes  transparent  yellow  or  brown  by 

jjj  oblique  light. 

5  HARD.     High.  SURF.     Shiny,  pitted.  H.  6-7. 

r\  CHEM.     1.    HNO3 .     2.    HNO3    cone. .     3.    KCN .      4.    HC1 

cone. .     5.  Aq.  Reg. .     6.  FeCU .     7.  KOH . 

««%,  DIFP.     Col.     Chem.  inertness. 

>J  NOTE.     Very  hard  to  polish  free  from  pits. 

LIMONITE  2  Fe2O3-3  H2O  ? 

COL.  Gray.  With  galena,  pale  slate  gray  to  dull  gray;  with  sphaler- 
ite, slightly  bluish  gray.  Often  transparent  reddish  brown  or  yellow 
by  oblique  light.  Color  appears  brighter  on  a  smooth  surface  than 
on  a  rough  one. 

HARD.     High.  SURF.     Smooth,  or  pitted.  H.  5-5.5. 

CHEM.  1.  HNO3 .  2.  KCN .  3.  HC1  cone, .  4.  Aq.  Reg. 

.  5.  FeCk .  6.  KOH . 

DIFF.     Col.     Chem. 

CHROMITE  FeCr,O« 

COL.     Gray.     With  galena,  very  dull  gray;   with  sphalerite,  darker, 

dull  gray. 

HARD.     High.           SURF.     Shiny,  much  pitted.  H.  5.5. 

CHEM.     1.  HNOs .     2.  KCN .     3.  HC1  cone. .     4.  Aq.  Reg. 

DIFF.'   Col     Surf. 

NOTE.     Very  hard  to  polish  free  from  pits. 


RUTILE         See  page  90. 
FRANKLINITE         See  page  144. 
U  HEMATITE         See  page  90. 

§ 

^  ILMENITE         See  page  90. 

G 


146 


E 

O 

E 

Aq.  Reg. 


URANINITE  (A  uranate  of  uranyl  with  other  bases)  Q 

COL.     Gray.     With  sphalerite,   slightly  darker  and  faintly  brown-  ON 

ish  (?).  ^ 

HARD.     High.                     SURF.     Smooth.                            H.  5.5  >  si.  w 

CHEM.     1.  HNOs .      2.  KCN .     3.  HC1 .     4.  HC1  cone, .  *« 

5.  Aq.  Reg.     Slowly  blackens,  rubs  off  to  darker  gray,  roughened 

surface.     6.  FeCls.     Slowly  darkens,  roughens  slightly,  persistent. 

7.  KOH . 

DIFF.     Col.     Chem.  5,  6 


s 

UJ 


UJ 

Q 
Q^ 

E 


£ 

s 

I 

o 
< 


GRAY 

HARDNESS  MEDIUM 


HC1  Neg. 


SPHALERITE  ZnS 

COL.     Gray.     With  galena,  bright  steely  gray.     Sometimes  bluish,  or 

slate  gray,  or  reddish  when  in  very  small  areas.     Transparent  yellow 

to  brown  by  oblique  light.     Color  only  slightly  different  for  black  and 

for  pure  varieties. 

HARD.     Medium.  SURF.     Smooth.  H.  3.5-4  =or  >  cp. 

CHEM.     1.   HNO3.     Faintly  browned,  slowly,  often  showing  crystal 

structure.    2.  HNO3  cone.     Same.    3.   KCN .     4.   HC1 .     5. 

HC1  cone. .     6.  Aq.  Reg.     Instantly  effervesces  and   blackens. 

Rubs  off  to  show  rough  etched  surface.     Fumes  tarnish  brown.     7. 

FeCls .     8.      KOH .     9.     (NH^Sx .      10.     K4Fe(CN)6 . 

11.  K3Fe(CN)6 .     12.  Iodine .     13.  NH4OH . 

DIFF.         Col.     Chem.  1. 


WURTZITE  ZnS 

COL.     Gray.     Transparent  yellow  or  brown  by  oblique  light.     Same 

color  as  sphalerite. 

HARD.     Medium.  SURF.     Smooth.  H.  3.5-4. 

CHEM.     1.  HNOs.     Slowly  faint  brown.     2.  HNO3  cone.     Same.     3. 

KCN .    4.    HC1 .     5.    HC1    cone. .     6.    Aq.    Reg. .     7. 

FeCl3 .     8.  KOH — r. 

DIFF.     Chem.  1. 


VOLTZITE  Zn5S4O 

COL.     Gray.     With   sphalerite,    slightly  lighter   gray.  Transparent 

reddish  yellow  or  brown  by  oblique  light. 

HARD.     Medium.               SURF.     Smooth.  H.  4-4.5. 

CHEM.    1.  HNO3 .    Fumes  tarnish  faintly.    2.  KCN .    3.  HC1 . 

4.  Aq.  Reg. .    Fumes  tarnish  brown.     5.  FeCls .     6.  KOH . 

DIFF.     Chem.  1. 


ER  YTHROZINCITE  (MnZn)  S 

COL.     Gray.     About  like  limonite. 
Occ.     Coatings  and  yeinlets  on  and  in  pyrite. 
HARD.     Low  to  medium.     SURF.     Smooth.  H. 

CHEM.     1.  HNO3 ?     2.  KCN .     3.  HC1 .     4.   Aq.  Reg. . 

5.  FeCls .     6.  KOH . 

DIFF.     Chem.  1,  4. 


URANINITE         See  page  147. 
ARGYRODITE        See  page  105. 


148 


HC1 


CUPRODESCLOIZITE 

\—  •»'— MV»»/*  »  2vy-*AZW 

GOL.  Gray.  With  galena,  dull  gray.  Sometimes  transparent  green- 
ish or  brownish  with  oblique  light. 

HARD.     Medium.               SURF.     Smooth.         -V  H35 

CHEM.  1  HNO3.  Quickly  blackens  and  dissolves;  shows  yellow  coat 
ing  with  oblique  light.  2.  KCN— .  3.  HC1  same  as  HNO3  4. 
Aq.  Reg.  Dissolved,  coated  quickly  with  yellowish  green,  which 
shows  white  after  acid  is  washed  off.  Fumes  tarnish  iridescent  in- 
stantly,  then  tarnish  turns  black.  5.  FeCla .  6.  KOH -. 


DIFF.     Chem.  1. 


CUPRITE        See  page  117. 
ALABANDITE        See  page  96. 

Q 

TENORITE         See  page  92.  S 

DELAFOSSITE        See  page  92.  CO 

Q 


s 


U 

a 


GRAY 
HARDNESS  Low 


LORANDITE  TlAsS2 

GOL.  Gray.  With  galena,  distinctly  gray;  with  sphalerite,  slightly 
darker.  Transparent  orange  red  by  oblique  light. 

HARD.     Low.  SURF.     Smooth. 

CHEM.  1.  HNO3 .  2.  KCN .  3.  HC1 .  4.  Aq.  Reg. .  5. 

FeCla .  6.  KOH.  Instantly  coated  with  orange.  Rubs  off  to 

show  very  rough  solution  surface. 

DIFF.     Chem.  6. 


STANNITE        See  page  108. 
"PETZITE"         See  page  106. 
ARGYRODITE        See  page  105. 
ERYTHROZINCITE         See  page  148. 
TAPALPAITE  "  (GRAY)         See  page  107. 


160 


I 

Q 


151 


MISCELLANEOUS  TABLES 


INDEX 


CONDENSED  DETERMINATIVE  TABLE 

The  more  important  minerals  are  printed  in  conspicuous  type, 
so  that  they  can  be  readily  picked  out.  The  parentheses  around  a 
mineral  name  indicate  that  the  reaction  changes  in  character  as  it 
progresses,  and  that  the  first  stage  places  the  mineral  in  a  certain 
group,  while  the  final  effect  puts  it  elsewhere.  For  example,  mar- 
casite  first  turns  brown,  and  then  finally  blackens,  with  HNO3,  and 
so  is  referred  to  in  parentheses  under  HNO3  —  Eff.  —  Browns,  and 
without  parentheses  under  HNO3  —  Eff.  —  Blackens  —  FeCl3  neg. 

HNO3  Neg. 


KCN  neg. 

KCN 

Aq.  Reg.  neg. 

KOH  neg. 

Cassiterite                      Lorandite 

Argentite 

Chromite                        Magnetite 

Argyrodite 

Erythrozincite               Millerite 

Covellite 

Franklinite                    Molybdenite 

Gold 

Hematite                       Rutile 

Jalpaite 

Ilmenite                         Sartorite 

Onofrite 

Lehrbachite 

Polybasite 

Limonite 

Aq.  Reg. 

KOH 

No  Eff. 

Eff. 

Berthierite 

Bournonite 

Livingstonite 

Chalcostibite 

Dufrenoysite 

Miargyrite 

Chalcopyrite 

Kalgoorlite 

Orpiment 

Delafossite 

Lengenbachite 

Proustite 

Matildite  (?) 
Psilomelane 

(Onofrite) 
Rathite 

Pyrargyrite 
Stephanite 

Regnolite 

Schirmerite 

Sperrylite 

Seligmannite 

Tenorite 

Stiitzite 

Tiemannite 

Vrbaite 

Uraninite 

Fumes  HNO; 


Chalmersite 
Enargite 
Hauerite 
Luzonite 
Pearceite 
Polyargyrite 

Sulvanite 
Tennantite 
Tetrahedrite 
Voltzite 

HNO. 


No  Eff. 
Blackens 
FeCls  neg. 

Bismuthinite 
Cuprodescloizite 
Epiboulangerite 
Freieslebenite 
Galenobismutite 
Geocronite 
Gersdorffite 

Glaucodot 
Guejarite 
Jamesonite 
Jordanite 
Meneghinite 
Realgar 
Semseyite 

Eff. 
Blackens 
FeCl3  neg. 

Aikinite 
Alabandite 
Algodonite  (gray) 
Arsenopyrite 
Boulangerite 
Cinnabar 
Cosalite 

Marcasite 
Dognacskaite 
Horsfordite 
Mohawkite  (cream) 
Niccolite 
Zinkenite 

154 


OF  THE  OPAQUE  MINERALS 


155 


No  Eff.  (continued') 


Eff.  (continued) 


FeCls 

Breithauptite 
Clausthalite 
Euoairite 
Galena 
SUver 
Tetradymite 

fr  T 

;-P 

FeCl3 

Algodonite  (cream) 
Arsenic 
Bismuth 
Chilenite 
Cuprite 
Hessite  (?) 
Huntilite 
Maucherite 
Melonite 
Mohawkite  (gray) 

Naumannite 
Petzite  (?) 
Rickardite 
Safflorite 
Skutterudite 
Smaltite 
Steinmannite 
Tapalpaite 
Tellurium 

Browns 
Slowly 

Aguilarite 
Baurnhauerite 
Brogniardite 
Cobaltite 
Coloradoite 
Crookesite 
Cylindrite 
Famatinite 
Hauchecornite 
Kermesite 
Linnaeite 
Lollingite 

Matildite  (?) 
Metacinnabarite 
Pentlandite 
Polydymite 
(Polytelite) 
Pyrrhotite 
Sphalerite 
Stylotypite 
Wittichenite 
Wurtzite 

Browns 

Altaite 
(Arsenic) 
Bornite 
Calaverite 
Petzite 
Pyrite 
Whitneyite 
Willyamite 
(Marcasite) 

> 

Quickly 

Chloanthite 
Emplectite 
Frankeite 
(Galenobismutite) 
Hessite 
(Jamesonite) 
Rammelsbergite 

(Stannite) 
Stibnite 
Sylvanite 

(Teallite) 
(Tetradymite) 
(Ullmannite) 
"  Bronze  Enargite  " 

Turns  iridescent 
FeCls  neg. 

Andorite 
Beegerite 
(Cylindrite) 
(Frankeite) 
Freibergite 
(Gersdorffite) 
Guanajuatite 
(Guejarite) 
Guitermanite 

Lengenbachite 
Nagyagite 
Polytelite 
Semseyite 
Stannite 
Stern  bergite 
Ullmannite 

Turns  iridescent 

(Arsenopyrite) 
Chiviatite 
(Dognacskaite) 
Kallilite 
(Steinmannite) 
(Willyamite) 

FeCls 

Berzelianite 
(Breithauptite) 
(Coloradoite) 
Dyscrasite 

(Hessite) 
Lillianite 
Rezbanyite 
Teallite 

Turns  blue 

Umangite 

Turns  blue 
Chalcocite 

Color  unchanged 

Copper 
Stromeyerite 

Color  unchanged 
Realgar 

ODOR  AND  STREAK  OF  MINERALS 

A  number  of  minerals  carrying  arsenic  give  off  a  characteristic 
odor  when  ground  dry  on  the  coarse  carborundum  wheel.  Many 
arsenic  minerals  do  not  give  this,  however,  so  absence  of  odor  does 
not  necessarily  mean  absence  of  arsenic.  Selenium  occasionally 
gives  an  odor  under  the  same  conditions.  Some  minerals  leave  a 
characteristic  streak  when  polished  on  the  canvas  wheel.  These 
several  groups  of  minerals  are  listed  below. 

ARSENIC   ODOR 

Arsenic  Lollingite 

Arsenopyrite  Safflorite 

Chloanthite  Smaltite 

Glaucodot  Skutterudite 

(Enargite  under  some  conditions,  but  not  usually) 

SELENIUM    ODOR 
Eucairite 

(Probably  some  other  selenides  also,  but  none  were  obtained  large  enough  to  test  fairly 
in  this  respect.) 

STREAK 

Tetrahedrite  —  reddish 
Tennantite  —  reddish 
Hauerite  —  orange 
Sphalerite  —  brown  to  whitish 
Limonite  —  brown  to  reddish 


156 


MINERALS  TABULATED  BY  ELEMENTS 

(Brackets  indicate  that  the  enclosed  mineral  has  not  been  studied  in  this  investigation) 


ARSENIC 


Algodonite     CueAs  (mixture) 

Argyropyrite    Ag,  Fe,  S,  As 

Arsenic     As 

Acsenopyrite     FeAsS 

[Badenite     (CoFeNi)2(AsBi)8] 

Baumhauerite     Pb4AseSi3 

"Bronze  Enargite"     (CuSn),  (AsSb),  83  ? 

Chloanthite     NiAsz 

Cobaltite     CoAsS 

Domeykite     CusAs  (+Sb)  (mixture) 

Dufrenoysite     Pb2As2S6 

Enargite     Cu3AsS4 

[Epigenite     R7As2Si2  (R  =  8  Cu  +  3  Fe)] 

Gersdorffite     NiAsS 

Glaucodot     (CoFe)AsS 

Guitermanite     PbsAsaSe 

Huntilite     AgsAs  ? 

[Hutchinsonite     Tl,  Ag,  Cu,  Pb,  As,  S  ?] 

Jordanite     Pb4As2Sr 

Kallilite     NiBiS  +  As,  Sb  ? 

Lengenbachite     Pbs(AgCu)  ^34818 

[Liveingite     PbsAssSi?] 

Lollingite     FeAs2 

Lorandite     TlAsS2 


Luzonite     CusAsS4 
Maucherite     NisAss 
Mohawkite     CusAs  (mixture) 
Niccolite     NiAs 
Orpiment     As2Sa 
Pearceite     Ag9AsS« 
Proustite     Ag3AsS3 
Rammelsbergite     NiAss 
Rathite    Pb,  As,  Sb,  S  ? 
Realgar    AsS 
Regnolite     Cu7As2Si2 
Safflorite     CoAs2 
Sartorite     PbAs2S4 
Seligmannite     CuPbAsSs 
Skutterudite     CoAss 
Smaltite     CoAs2 
[Smithite     AgAsS2] 
Sperrylite     PtAs2 
Steinmannite     Pb(As,  Sb,  S) 
Tennantite     CugAs2S7 
[Trechmannite     AgAsS2] 
Vrbaite     TlAs2SbS5 
Whitneyite     CuoAs 
[Xanthoconite 


ANTIMONY 


Andorite 

Berthierite     FeSb2S4 

Boulangerite     PbsSb^o 

Bournonite     (PbCu2)3Sb2S6 

Breithauptite     NiSb 

Brogniardite     PbAg2Sb2S5  ? 

"  Bronze  Enargite  "     (CuSn),  (AsSb),  S  ? 

Chalcostibite     CuSbS2 

Cylindrite     3  PbSnS2  +  SnFeSb2S8 

[Diaphorite     (PbAg2)5Sb4Sn] 

Domeykite     CuaAs  +  (Sb)  (mixture) 

Dyscrasite     AgeSb 

[Eichbergite     (CuFeJBiaSbsSs] 

Epiboulangerite     PbsSb2S8 

Famatinite     Cu3SbS4 

Frankeite     3  PbSnS2  +  PbsFeSbtSg 

Freibergite     (CuAg)  8Sb2S7 

Freieslebenite     (PbAg2)5Sb4Su 

Geocronite     Pb5Sb2S8 

Guejarite     Cu2Sb4S7 

Hauchecornite     (NiCo)7(BiSbS)8 

[Histrixite     Cu5Fe5Bi14Sb4S37  (mixture)  ?] 

Horsfordite     CueSb  ? 

Jamesonite     Pb2Sb2S6 

Kallilite     NiBiS  +  As,  Sb  ? 

Kermesite     Sb2S2O 


Kobellite     Pb2(BiSb)2S5  (mixture  ?) 

Livingstonite     HgSb4S? 

Meneghinite     Pb4Sb2S7 

Miargyrite     AgSbS2 

Nagyagite     Au2Pbl0Sb2Te6Si8 

Plagionite     PbsSbsSn 

Polyargyrite     Ag24Sb2Sis 

Polybasite     Ag9SbS6 

Polytelite     (PbAgFeZn)4Sb2S7  ? 

Pyrargyrite     AgsSbSs 

[Pyrostilpnite     Ag3SbS3] 

Rathite    Pb,  As,  Sb,  S  ? 

[Richmondite     ReSb2S9  (R  =  Pb,  Cu,  Ag,  Fe, 

Zn)] 

[Sampsonite"    (Ag4Mn)Sb2S«] 
Semseyite     PbrSbeSw 
Stephanite     AgBSbS4 
(Steinmannite)     Pb(As,  Sb,  S) 
Stibnite     Sb2S3 

Stylotypite     (Cu2Ag2Fe)sSbi& 
Tetrahedrite     CusSbsS? 
Ullmannite     NiSbS 
Vrbaite    TlAs2SbSB 
Willyamite     (CoNi)SbS 
Zinkenite    PbSb2S4 


157 


158 


MICROSCOPICAL  DETERMINATION 


BISMUTH 


Aikinite    PbCuBiSj 
[Badenite     (CoFeNi),(AsBi),] 
Beegerite     PbeBi2S» 
Bismuth     Bi 
Bismuthinite    BijSs 
Chilenite    Ag«Bi  ? 
Chiviatite     Pb2Bi«Sn 
Cosalite    PbzBizSs 
[Cuprobismutite     CueBigSu] 
Dognacskaite    Bi,  Cu,  S  ? 
[Eichbergite     (CuFe)Bi3Sb8S6] 
Emplectite     CuBiS* 
Galenobismutite     PbBi2S4 
[Grunlingite     Bi4TeSs] 
Guanajuatite     Bi2Se3 
Hauchecornite     (NiCo)7(Bi,  S,  Sb)8 


[Histrixite 

KaUiUte    Ni,  Bi,  S  ?  (+Sb,  As) 

Klaprotholite     GueBi4S« 

Kobellite     Pb2(BiSb)2S8  (mixture?) 

Lillianite     PbsBi^ 

Matildite     AgBiSs 

[Platynite     PbBi2Sa] 

Plenargjrrite     AgBiS2  ? 

Rezbanyite     Pb4BiioS19 

Schapbachite     PbAg2Bi2S6  ?  (mixture) 

Schirmerite     (Ag2Pb)3Bi4S9 

Tapalpaite    3  Agz(S,  Te)-Bi2CSTe)« 

Tetradymite    Bi2(TeS)3 

[Von  Diestite    Ag,  Bi,  Te  ?] 

[Weibullite    Pb2Bi4S5Se3] 

Wittichemte    CuaBiSs 


[Greenockite     CdSJ 


[Oldhamite     CaS] 


CADMIUM 


CALCIUM 


Chromite     FeCr2O4 


CHROMIUM 

[Daubreelite    FeCrtSi] 


[Badenite     (CoFeNi)2(AsBi)3] 
Cobaltite     CoAsS 
Glaucodot     (CoFe)AsS 
Hauchecornite     (NiCo)  7(Bi,  S,  Sb) a 
Linnaeite 


COBALT 

Safflorite    CoAst 
Skutterudite     CoAsa 
Smaltite     CoAs, 
[Sychnodymite     (CoCu)4S]  ? 
WiUyamite     (CoNi)SbS 


OF  THE  OPAQUE  MINERALS 


159 


COPPER 


Aikinite     PbCuBiSj 

Algodonite     Cu&As  (mixture) 

Berzelianite     Cu2Se 

Bornite     Cu6FeS4 

Bournonite     (PbCuOsSb^e 

1 '  Bronze  Enargite ' '     (CuSn) ,  (SbAs) ,  S  ? 

Chalcocite     Cu2S 

Chalcopyrite     CuFeS2 

Chalcostibite     CuSbSj 

Chalmersite     CuFe2S3 

Copper     Cu 

Covellite     CuS 

Crookesite     (CuTlAg^e 

Cuprite     Cu2O 

[Cuprobismutite     CueBiaSu] 

Cuprodescloizite     (PbZnCu)  4V2O»-H2O 

Delafossite     Cu,  Fe,  O 

Dognacskaite     Bi,  Cu,  S  ? 

Domeykite     CuaAs  (  +Sb)  (mixture) 

[Eichbergite     (CuFe)Bi3Sb2S6] 

Emplectite     CuBiS2 

Enargite     CusAsS4 

[Epigenite    R7As2Si2  (R  =  8  Cu  +  3  Fe)  ] 

Eucairite     Cu2Se-Ag2Se 

Famatinite     CusSbS4 

Freibergite     (CuAg)8Sb2S7 


Guejarite 

[Histrixite     CmFesBii^b^?  (mixture)] 

Horsfordite     Cu6Sb 

[Hatchinsonite     Tl,  Ag,  Cu,  Pb,  As,  S  ?] 

Jalpaite     CuuS-3  Ag2S 

Klaprotholite     CueBi^* 

Lengenbachite     Pb6(AgCu)2As4Su 

Luzonite     Cu3AsS4 

Mohawkite     CusAs  (mixture) 

Regnolite     Cu7As2Si2 

[Richmondite     RoSb2S9  (R  =  Pb,  Cu,  Ag,  Fe, 

Zn)J 

Rickardite     Cu4Te3 
Seligmannite     CuPbAsSs 
Stannite     Sn,  Cu,  Fe,  Zn,  S  ? 
Stromeyerite     (AgCu)2S 
Stylotypite     (Cu2Ag2Fe)3Sb8S« 
Sulvanite     Cu3VS4 
[Sychnodymite     (CoCu)4S6  ?] 
Tennantite 
Tenorite     CuO 
Tetrahedrite 
Umangite     Cu3Se2 
Whitneyite     CuaAs 
Wittichenite     Cu3BiS» 


Argyrodite     Ag8GeS6 


Calaverite  AgAuTej 
Gold     Au 

Kalgoorlite  HgAu2Ag8Tee 

Nagyagite  Au2Pb10Sb2Te6Si5 


[Argentopyrite    Ag,  Fe,  S  ?] 

Argyropyrite     Ag,  Fe,  S,  As  ? 

Arsenopyrite     FeAsS 

[Badenite     (CoFeNi)2(AsBi)3] 

Berthierite     FeSb2S4 

Bornite     Cu8FeS4 

Chalcopyrite     CuFeS2 

Chalmersite     CuFe2S3 

Chromite     FeCr2O4 

Cylindrite     3  PbSnS2  +  SnFeSbuSs 

[Daubreelite     FeCr2S4] 

Delafossite     Cu,  Fe,  O 

[Eichbergite     (CuFe)Bi3Sb3S8] 

[Epigenite     R7As2Si2  (R  =  8  Cu  +  3  Fe)l 

Frankeite     3  PbSnS2  +  Pb2FeSbjS8 

Franklinite     FeaZnMnsCh 

Frieseite     AgFe2Ss 

Glaucodot     (CoFe)AsS 


GERMANIUM 

[Canfieldite    Ag8(SnGe)S8J 


GOLD 


Petzite     (AgAu)2Te 
[Speculite     AgAuTe] 
Sylvanite    AgAuTej 


IRON 


Hematite     Fe2O3 

[Histrixite     CusFesBiuSb^s?  (mixture)  J 

Ilmenite     FeTiO3 

Limonite     2  Fe2O3-3  H2O 

Lollingite     FeAs2 

Magnetite     Fe3O4 

Marcasite     FeSis 

Pentlandite     (FeNi)S 

Polytelite     (PbAgFeZn)4SbJS7  ? 

Pyrite    FeS» 

Pyrrhotite    FeS(S)z 

[Richmondite     R6Sb2S9  (R=  Pb,  Cu,  Ag,  Fe, 

Zn)] 

Stannite     (Sn,  Cu,  Fe,  Zn),  S 
Sternbergite    Ag2Fe5S§ 
Stylotypite     (Cu2Ag2Fe)3Sb2S« 
[Troilite    FeS] 


160 


MICROSCOPICAL  DETERMINATION 


LEAD 


PbAg2Sb2S5  ? 


Aikinite     PbCuBiSa 

Altaite     PbTe 

Andorite 

Baumhauerite 

Beegerite     Pb«Bi2S9 

Boulangerite 

Bournonite 

Brogniardite 

Chiviatite 

Clausthalite     PbSe 

Cosalite     Pb2Bi2S6 

Cuprodescloizite     (PbZnCu)4V2O8-H2O 

Cylindrite     3  PbSnS2  +  SnFeSbaSs 

[Diaphorite     (PbAg2)6Sb4Su] 

Dufrenoysite     Pb2As2S6 

Epiboulangerite     Pb3Sb2S8 

Frankeite     3  PbSnS2  +  PbzFeSbaSs 

Freieslebenite     (PbAg2)  6Sb4Su 

Galena     PbS 

Galenobismutite     PbBi2S4 

Geocronite     PbsSbizSg 

Guitermannite     PbsAs2Se 

[Hutchinsonite     Tl,  Ag,  Cu,  Pb,  As,  S  ?] 

Jamesonite     P^SbaSs 

Jordanite     Pb4As2S? 


Kobellite     Pb2(BiSb)2S6  (mixture?) 

Lehrbachite    PbSe  +  HgSe 

Lengenbachite     Pb6(AgCu)2As4S13 

Lillianite     Pb3Bi2S6 

[Liveingite     PbsAssSn] 

Meneghinite 

Nagyagite 

Naumannite     (Ag2Pb)Se 

Plagionite     PbsSbsSn 

[Platynite     PbBizSs] 

Polytelite     (PbAgFeZn)4Sb2S7  ? 

Rathite     Pb,  As,  Sb,  S  ? 

Rezbanyite     Pb4Bi10Si9 

[Richmondite     ReSbizSg  (R=  Pb,  Cu,  Ag,  Fe, 

Zn)] 

Sartorite    PbAs2S4 
Schapbachite     PbAg2Bi2S5  (mixture) 
Schirmerite     (Ag2Pb)3Bi4S9 
Seligmannite     CuPbAsS3 
Semseyite     Pb2Sb6S16 
Steinmannite     Pb(As,  Sb,  S) 
Teallite     PbSnS2 

Uraninite     U,  O,  Pb,  La,  Th,  Di,  Y,  etc.  ? 
[Weibullite     Pb2Bi4S6Se3] 
Zinkenite     PbSb2S4 


MANGANESE 


Alabandite     MnS 
Erythrozincite     (MnZn)S  ? 
Franklinite     Fe3ZnMn3O4 


Hauerite     MnS2 
Psilomelane     H4MnOs 
[Sampsonite     ( Ag4Mn)  Sb2S6  ] 


Cinnabar     HgS 
Coloradoite     HgTe 
Kalgoorlite     HgAu2AgeTee 
Lehrbachite     PbSe  +  HgSe 


MERCURY 

Livingstonite     HgSb4S? 
Metacinnabarite     HgS 
Onofrite     Hg(SSe) 
Tiemannite    HgSe 


MOLYBDENUM 


Molybdenite     MoS2 


NICKEL 


[Badenite     (CoNiFe)2(AsBi)j] 
Breithauptite     NiSb 
Chloanthite     NiAs2 
Gersdorffite     NiAsS 
Hauchecornite     (NiCo)7(Bi,  S,  Sb)8 
Kallilite     NiBiS(AsSb) 
Maucherite     NisAsj 
Melonite    NizTei 


Millerite     NiS 
Niccolite     NiAs 
Pentlandite     (FeNi)S 
Polydymite     Ni^j 
Rammelsbergite     NiAsz 
Ullmannite     NiSbS 
Willyamite     (CoNi)SbS 


OF  THE  OPAQUE  MINERALS 


161 


OXYGEN 


Cassiterite     SnO2 

Chromite     FeCr2O4 

Cuprite     Cu2O 

Cuprodescloizite     (PbZnCu)4VjO»-H»O 

Delafossite     Cu,  Fe,  O       * 

Franklinite     FesZnMnaCh 

Hematite     Fe2O3 

Ilmenite     FeTiOs 


Kennesite     SbzSjO 

Limonite     2  Fe2O3-3  HjO 

Magnetite     FesO4 

Psilomelane     H4MnOe 

Rutile    TiO» 

Tenorite     CuO 

Uraninite    U,  O,  Pb,  La,  Th,  Di,  Y,  etc.  ? 

Voltzite 


Sperrylite    PtAsz 
[Laurite     RuAs2] 


PLATINUM 


RUTHENIUM 


SELENIUM 


Aguilarite     Ag2S-Ag2Se 
Berzelianite     Cu2Se 
Clausthalite     PbSe 
Crookesite     (CuTlAg)2Se 
Eucairite     (CuAg)2Se 
Guanajuatite     Bi2Se3 


Lehrbachite    PbSe  +  HgSe 
Naumannite     (Ag2Pb)Se 
Onofrite     HgSSe 
Tiemannite     HgSe 
Umangite     Cu3Se2 
[Weibullite 


SILVER 


Aguilarite     Ag2S-Ag2Se 

Andorite     Pb2Ag2SbeS9 

Argentite     Ag2S 

[Argentopyrite     Ag,  Fe,  S  ?] 

Argyrodite     AgeGeSs 

Argyropyrite     Ag,  Fe,  S,  As  ? 

Brogniardite     PbAg2Sb2S6  ? 

Calaverite     AgAuTe2 

[Canfieldite     Ag8(SnGe)S8] 

Chilenite     AgeBi 

Crookesite 

[Diaphorite 

Dyscrasite     AgeSb 

Eucairite     (CuAg)2Se 

Freieslebenite     (PbAg2)  5Sb4Su 

Freibergite     (CuAg^bsSi 

Frieseite,     AgFe2S3 

Hessite     Ag2Te 

Huntilite     AgsAs  ? 

[Hutchinsonite     Tl,  Ag,  Cu,  Pb,  As,  S  ?1 

Jalpaite     3  Ag2S-Cu2S 

Kalgoorlite     HgAu2Ag6Te6 

Lengenbachite 

Matildite     AgBiS2 

Miargyrite     AgSbS2 

Naumannite     (Ag2Pb)Se 

Pearceite     Ag»AsS« 


Petzite     (AgAu)2Te 

Plenargyrite     AgBiS2  ?  (mixture) 

Polyargyrite     Ag24Sb2SiS 

Polybasite     Ag9SbS6 

Polytelite     (PbAgFeZn)4Sb2S7  ? 

Proustite     AgsAsSs 

Pyrargyrite     AgsSbSs 

[Pyrostilpnite     Ag3SbS3] 

[Richmondite     R6Sb2S9  (R  =  Pb,  Cu,  Ag,  Fe, 

Zn)] 

[Sampsonite     (Ag4Mn)Sb2S6] 
Schapbachite    PbAg2Bi2S5  (mixture) 
Schirmerite     (Ag2Pb)3Bi4S» 
Silver     Ag 
[Smithite    AgAsS2] 
[Speculite    AgAuTe] 
Stephanite     Ag5SbS4 
Sternbergite     Ag2FesS3 
Stromeyerite     (AgCu)^ 
Stutzite    Ag4Te  ? 
Stylotypite     (Cu2Ag2Fe)3Sb»S, 
Sylvanite    AuAgTe2 
Tapalpaite    3  Ag2(STe)-Bi2(STe)8 
[  Trechmannite     AgAsS2  ] 
[Von  Diestite     Ag,  Bi,  Te  ?] 
[Xanthoconite    AgsAsS4] 


162  MICROSCOPICAL  DETERMINATION 


TELLURIUM 

Altaite     PbTe  Rickardite     Cu4Tes 

Calaverite     AgAuTej  [Speculite     AgAuTe] 

Coloradoite     HgTe  Stiitzite     Ag4Te  ? 

[Grttnlingite     Bi4TeS8  ?J  Sylvanite    AuAgTe2 

Hessite     Ag2Te  Tapalpaite    3  Ag2(STe)-Bi2(STe)8 

Kalgoorlite     HgAu2Ag«Te«  Tellurium     Te 

Melonite     Ni2Te3  Tetradymite     Bi2(TeS)s 

Nagyagite     Au2PbioSb2Te«Si5  [Von  Diestite     Ag,  Bi,  Te  ?J 
Petzite     (AgAu)2Te 

THALLIUM 

Crookesite     (CuTlAg)2Se  Lorandite     TlAsS» 

[Hutchinsonite     Tl,  Ag,  Cu,  Pb,  As,  S  ?]  Vrbaite     TlAs2SbS6 


THORIUM 

(with  Lanthanum,  Yttrium,  Nitrogen,  etc.) 
Uraninite     U,  O,'Y,  N,  Di,  Th,  La,  etc. 


TIN 

" Bronze  Enargite"     (CuSn),  (SbAs),  S  ?  Stannite     Sn,  Cu,  Fe,  Zn,  8 

Cassiterite     SnO2  Teallite,     PbSnS2 

Cylindrite     3  PbSnS2  +  SnFeSb2Ss  [Canfieldite     Ag8(SnGe)S6] 
Frankeite     3  PbSnSj  +  Pb2FeSb2S8 


I  TITANIUM 

Ilmenite     FeTiOi  Rutile    TiOj 

URANIUM 

Uraninite     U.  O,  Pb,  Y,  N,  Di,  La,  Th,  etc. 

VANADIUM 

Cuprodescloizite     (PbZnCu)4V2O»-H2O  Sulvanite 

[Patronite    VS4  ?  ] 

ZINC 

Cuprodescloizite     (PbZnCu)4V2O9-H2O  Sphalerite    ZnS 

Erythrozincite     (ZnMn)S  ?  Stannite    Sn,  Cu,  Fe,  Zn,  S 

Franklmite     FesZnMr^  Voltzite    Zn8S4O 

Polytelite     (PbAgFeZ^^bzST  Wurtzite    ZnS 
(Richmondite    RaSb2S9  (R  =  Pb,  Cu,  Ag,  Fe, 
Zn)] 


INDEX  OF  MINERALS 


The  number  in  parentheses  after  each  name  indicates  the  number 
of  localities  from  which  material  has  been  studied,  (n)  indicates 
more  than  5  localities.  The  letter  or  symbol,  in  the  case  of  single 
specimens,  indicates  the  probable  value  of  the  specimen  as  a  repre- 
sentative of  its  species.  G  =  reliable.  F  =  fairly  reliable.  ?  = 
doubtful. 


MINERAL 

Aguilarite  (1)  G 

Aikinit.fi  (1)  G 

Alabandite  (3) 

Algodonite  (mixture)  (1) . 

Cream  constituent 

Gray  constituent 

Alloclasite  (mixture  ?)  (1) 

Altaite  (3) 

Andorite  (1)  G 

Animikite  (mixture  ?)  (1). 

Argentite  (4) 

Argyrodite  (2) 

Argyropyrite  (1)  ? 

Arsenic  (2) 

Arsenopyrite  (n) 


PAGE 

10A 

101 

96 

37 

74 

96 

37 

128 

134 

37 

107 

105 

101 

136 

82 


Barnhardtite  (mixture)  (1) 

Baumhauerite  (1)  G 

Beegerite  (1)  G 

Berthierite  (3) 

Beraelianite  (1)  G 

Bismuth  (n) 

Bismuthinite  (3} 

Antimonial  (1)  G 

Bornite  (n) 

Boulangerite  (2) 

Bournonite  (4) 

Breithauptite 

Brogniardite  (1)  ? 37, 

Calaverite  (1)  G 

Carrollite  (mixture  ?)  (1) 

Gassiterite  (3) 

Chalcocite  (n) 

Chalcopyrrhotite  (mixture)  (1) 

Chalcostibite  (1)  G 

Chalcopyrite  (n) 

Chalmersite  (3) 

Ctolenite  (1)  G 

Chiviatite  (1)  G 

Chloaathite  (2) 


37 
108 
134 
103 
131 
125 
130 
131 

65 
135 

92 

66 
110 

124 

37 

146 

107 

37 

102 

62 

72 

125 

120 

85 


MINERAL 


PAGE 


Chromite  (2) 146 

Cinnabar  (2) 141 

Clausthalite  (1)  G 128 

Cobaltite  (2) 86 

Coloradoite  (1)  G 106 

Copper  (n) 67 

Cosalite  (1)  F 122 

Covellite  (n) 58 

Crookesite  (1)  F 108 

Cubanite  (mixture)  (4) 37 

Cuprite  (n) 117 

Cuprodescloizite  (1)  G 149 

Cylindrite  (1)  G 110 

Delafossite  (1)  G 92 

Dognacskaite  (1)  G 135 

Domeykite  (2) 37,  125 

Dufrenoysite  (1)  G 142 

Dyscrasite  (2) 125 

Emplectite  (3) 122 

Enargite  (n) 95 

Epiboulangerite  (1)  G 134 

Erythrozincite  (1)  G 148 

Eucairite  (1)  G 130 

Famatinite  (3)  ? 99 

Frankeite  (1)  G 110 

Franklinite  (1)  G 144 

Freibergite  (2) 94 

Freieslebenite  (1)  G 134 

Galena  (n) 133 

Galenobismutite  (1)  ? 130 

Geocronite  (1)  F 132 

Gersdorffite  (2) 88 

Glaucodot  (1)  G 87 

Gold  (n) 62 

Guanajuatite  (1)  G 120 

Guejarite  (1)  G 103 

Guitermanite  (1)  G 134 


163 


164 


MICROSCOPICAL  DETERMINATION 


MINERAL 


PAGE 


Harrisite  (pseudomorph)  (1)  G 38 

Hauchecornite  (2) 79 

Hauerite  (2) 94 

Hematite  (n) 90 

Hessite  (2) 138 

Homichlin  (mixture)  (1)  G 38 

Horsfordite  (1)  G 135 

Huntilite  (1)  F 119 

Ilmenite  (5) 90 

Jalpaite  (1)  F 140 

Jamesonite  (2) 110 

Jordanite  ?  (1)  ? 134 

Kalgoorlite  (1)  G 124 

Kallilite  (1)  F 82 

Kermesite  (1)  G 138 

Keweenawite  (mixture)  (2) 38 

Klaprotholite  (mixture  ?)(!)? 38 

Kobellite 38 

Krennerite  (1)  G 124 

Lehrbachite  (1)  F 131 

Lengenbachite  (1)  G 141 

Lillianite  (1)  G 133 

Limonite  (n) 146 

Linnaeite  (2) 79 

Livingstonite  (1)  G 142 

Lollingite  (2) 84 

Lorandite  (1)  G 150 

Luzonite  (3  ?) 98 

Magnetite  (n) 91 

Marcasite  (n) 78 

Matildite  (1)  G 140 

Maucherite  (2) 79 

Melonite  (1)  G 124 

Meneghinite  (1)  G 132 

Metacinnabarite  (1)  G 122 

Miargyrite  (1)  G 115 

Millerite  (3) 63 

Mohawkite  (mixture)  (1)  G 38 

Cream  constituent 74 

Gray  constituent 97 

Molybdenite  (4) 104 

Nagyagite  (2) 134 

Naumannite  (1)  G 128 

Niccolite  (n) 66 

Onofrite  (1)  F 114 

Orpiment  (2) 105 

Pearceite  (1)  F 105 

Pentlandite  (1)  G 100 

Petzite  (2) 137 

Plagionite  (1)  G 135 

Plenargyrite  (mixture)  (1)  F 38 

Hard  constituent 136 

Soft  constituent 116 

Polyargyrite  (1)  G 114 


MINERAL  PAGE 

Polybasite  (3) 105 

Polydymite  (2) 82 

Polytelite  (1)  ? 96 

Proustite  (n) 115 

Psilomelane  (2) 144 

Pyrargyrite  (6  ?) 115 

Pyrite  (n) 78 

Pyrrhotite  (n) 76 

Rammelsbergite  (1)  G 85 

Rathite  (1)  G 141 

Realgar  (3) 108 

Regnolite  (1)  G 104 

Rezbanyite  (1)  G 136 

Rickardite  (1)  G 60 

Rutile  (2) 90 

Safflorite  (1)  G 83 

Sartorite  (1)  F 142 

Schapbachite  (mixture)  (1)  F 38 

Hard  constituent 137 

Soft  constituent 116 

Schirmerite  (1)  F 141 

Seligmannite  (1)  G 104 

Semseyite  (1)  G 132 

Silver  (n) 118 

Skutterudite  (1)  ? 83 

Smaltite  (3) 38,  83 

Sperrylite  (1)  G 91 

Sphalerite  (n) 148 

Stannite  (3) 108 

Steinmannite  (var.  Galena)  (1)  G 133 

Stephanite  (2) .  142 

Sternbergite  (1)  G 65 

Stibnite  (3) 138 

Stromeyerite  (3) 117 

Stutzite  (1)  G 114 

Stylotypite  (1)  F 97 

Sulvanite  (1)  G 72 

Sylvanite  (2) 122 

Tapalpaite  (mixture  ?)  (1)  G 38, '125 

Teallite  (1)  G 106 

Tellurium  (3) 130 

Temiskamite  (mixture)  (1)  G 38 

Tennantite  (n) 94 

Tenorite  (2) 92 

Tetradymite  (2)  ? 133 

Tetrahedrite  (n) 94 

Tiemannite  (1)  G 114 

Ullmannite  (1)  G 84 

Umangite  (3) 60 

Unknown  minerals: 

Algodonite  cream 74 

gray 96 

"  Alloklas"  from  Orawitaa 136 

Argentiferous  "Jamesonite" 104 


OF  THE  OPAQUE  MINERALS 


165 


MINERAL 


PAGE 


4'Brogniardite"  (near  andorite)  ....  134 

Bluish  white,  Joachimsthal 115 

Bluish  white,  Tonopah r/ .  114 

"  Bronze  Enargite  " ; . . . .  74 

Coffee  brown ^  .  65 

Creamy  bismuth  minertd 126 

Grayish  bismuth  mineral 97 

"Hessite" 118 

" Matildite"  Japan 120 

Mohawkite  cream 74 

gray 97 

Orange  " bornite" 64 

"Petzite" 106 

Pink  mineral  in  mohawkite 76 

Purple  "bornite" 65 

Purple  "galena" 116 


MINERAL  PAGE 

Plenargyrite,  hard  constituent 136 

Soft  constituent 116 

Schapbachite,  hard  constituent 137 

Schapbachite,  soft  constituent 116 

"  Tapalpaite"  Gray 107 

Pure  white  mineral,  Bisbee 130 

Uraninite  (1)  G 147 

Voltzite  (1)  G 148 

Vrbaite  (1)  G 115 

Whitneyite  (1)  G 74 

Willyamite  (1)  G 82 

Wittichenite  (1)  F 121 

Wurtzite  (1)  G 148 

Zinkenite  (2) Ill 


f»  ; 
A 


34024? 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


iiii 


i      u 


1  ilii 


